FILE - In this Saturday, Sept. 15, 2012 file photo, newly-arrived Syrian refugees having crossed the border from Tal Shehab city in Syria through the Al Yarmouk River valley walk towards Ramtha, Jordan. Jordan is home to than 425,000 registered refugees, and the numbers are growing daily by 2,000 to 3,000. Most of the Syrians are staying in the Zaatari refugee camp, and authorities are building another camp to manage the massive surge. (AP Photo/Raad Adayleh) This citizen journalism image provided by Lens Young Homsi, which has been authenticated based on its contents and other AP reporting, shows Syrian rebels standing in the rubble of damaged buildings due to government airstrikes, in Homs, Syria, Wednesday, March. The chief of staff of the rebel army pleaded with the international community Wednesday to supply arms and ammunition so the opposition can resist attacks by the regime of Syria's President Bashar Assad. AP Photo/Lens Young Homsi FILE - In this Thursday, Dec. 20, 2012 file photo, Syrian refugees,who fled their home in Idlib due to a government airstrike load their belongings into a vehicle just after crossing the border from Syria to Turkey, in Cilvegozu, Turkey. Turkey is home to nearly 200,000 Syrian refugees in camps, with another 100,000 living on their own. The Turkish government has been funding and managing the refugees, whom they have sheltered in 17 camps that have schools, medical centers and other social facilities. AP Photo/Muhammed Muheisen, File BEIRUT (AP) - Syria's accelerating humanitarian crisis hit a grim milestone Wednesday: The number of U.N.-registered refugees topped 1 million - half of them children - described by an aid worker as a "human river" of thousands spilling out of the war-ravaged country every day. Nearly 4 million of Syria's 22 million people have been driven from their homes by the civil war. Of the displaced, 2 million have sought cover in camps and makeshift shelters across Syria, 1 million have registered as refugees in neighboring Turkey, Jordan, Lebanon, Iraq and Egypt, and several hundred thousand more fled the country but haven't signed up with the U.N. refugee agency. The West has refrained from military intervention in the two-year-old battle to oust Syrian President Bashar Assad, a conflict that has claimed more than 70,000 lives, and many Syrians hold the international community responsible for their misery. "The refugee numbers swelled because the world community is sitting idly, watching the tyrant Assad killing innocent people," said Mohammed Ammari, a 32-year-old refugee in the Zaatari camp straddling Jordan's border with Syria. Shame, shame, shame. The world should be ashamed. Despite an overall deadlock on the battlefield, the rebels have made recent gains, especially in northern Syria. On Wednesday, they completed their capture of Raqqa, the first major city to fall completely into rebel hands, activists said. But with no quick end to the conflict in sight, the refugee problem is bound to worsen, said Panos Moumtzis of the U.N. refugee agency, UNHCR. The number of uprooted Syrians is still lower than those displaced in other conflicts, including Afghanistan, Iraq and the Balkans, but the Syria crisis will likely be protracted, and widespread devastation will make quick repatriation unlikely. "We fear that the worst may not have come yet," Moumtzis said. The exodus from Syria picked up significantly in recent months, turning into a "human river flowing in, day and night," he added. The number of registered refugees doubled since December, he said, with some 7,000 fleeing Syria every day. Many refugees moved from shelter to shelter in Syria first before deciding to leave the country, while others were driven out by the increasing lack of basic resources, such as bread and fuel, in their hometowns. In the hardest-hit areas, entire villages have emptied out and families spanning several generations cross the border together. On Wednesday, a 19-year-old mother of two became the one-millionth Syrian refugee to register with UNHCR. She would only give her first name, Bushra, because she feared reprisals. Bushra waited with several others at a U.N. office in Lebanon's northern city of Tripoli to sign up. Along with her 4-year-old daughter, Batoul, and 2-year-old son, Omar, she fled fighting in the central city of Homs more than two weeks ago. Our life conditions are very bad. It is very expensive here (in Lebanon) and we cannot find any work," Bushra said. Only about 30 percent of the 1 million registered refugees live in 22 camps - 17 in Turkey, three in Jordan and two in Iraq - and the rest live in communities in host countries, Moumtzis said. Zaatari, one of the largest, is home to some 120,000 people. Refugees have been struggling with harsh desert conditions, including cold and floods in the winter, and scorching heat, along with snakes and scorpions, in the summer. Moumtzis said he recently met a woman in Zaatari with an ID that shows her to be 101 years old. The woman, from the southern Syrian town of Daraa, was carried by her relatives, he said. The U.N. refugee agency needs money to help overstretched host countries cope. Of the $1 billion in refugee aid pledged at a donor conference in Kuwait in January, only $200 million has come through, officials said. "We are doing everything we can to help, but the international humanitarian response capacity is dangerously stretched," said the U.N. High Commissioner for Refugees, Antonio Guterres, adding that "Syria is spiraling toward full-scale disaster." The uprising against Assad began in March 2011 with peaceful protests, but soon became a civil war. The rebel takeover of Raqqa, a city of 500,000, would consolidate opposition gains in the northern towns along the Euphrates River, which runs from Turkey to Iraq. The Britain-based Syrian Observatory for Human Rights, an activist group, said rebels seized control of the military intelligence headquarters and another security building after three days of fighting with regime holdouts. In southern Syria, rebel fighters detained about 20 U.N. peacekeepers Wednesday, said U.N. deputy spokesman Eduardo del Buey. The peacekeepers are part of a force that monitors a cease-fire between Israel and Syrian troops on the Golan Heights. In video circulated by the Observatory, a rebel identifying himself as a fighter from the "Yarmouk Brigade" walks along an armored U.N. vehicle. He accuses the peacekeepers of helping regime soldiers redeploy in an area near the Golan that the fighters had seized a few days earlier. Del Buey said the U.N. observers were on a regular supply mission when they were stopped by the rebels. He said a team was dispatched to try to resolve the issue. The Observatory quoted rebels as saying the peacekeepers, all Filipinos, would not be released until regime forces withdraw from a village called Jamla. The U.N. Security Council demanded their immediate and unconditional release. Peter Bouckaert, a researcher for the international group Human Rights Watch, said he is investigating suspicions, based on amateur video, that the same group of rebels was involved in the execution of captured regime soldiers in the area several days ago. In Belgium, the top rebel commander renewed an appeal to the international community to send weapons to the opposition. Gen. Salim Idris, head of the rebels' Supreme Military Council, asked for anti-tank and anti-aircraft missiles to protect Syrian civilians from Assad's warplanes. He said Russia and Iran are aiding the regime, while the West, while calling for Assad's ouster, is not doing enough to help the rebels. "The people don't understand why the international community just looks at the news on their TVs," he said. They just speak in the media and say, 'that is not good and the regime must stop and must go, Bashar must go.' And they don't act. Britain seemed to be stepping up its support. British Foreign Secretary William Hague said his country would provide armored vehicles, body armor and search-and-rescue equipment to the opposition. But he said Britain is sticking to the European Union's sanctions against Syria, which include an arms embargo. In Cairo, the 22-member Arab League gave a diplomatic boost to the opposition. The League's chief, Nabil ElAraby, offered Syria's seat to the opposition, provided it forms a representative executive council. The League had suspended Syria's membership in 2011, after Assad's government did not abide by an Arab peace plan. Associated Press writers Barbara Surk, Bassem Mroue and Zeina Karam in Beirut; Jamal Halaby in Amman; David Rising in Berlin; Don Melvin in Brussels; Jill Lawless in London; and Edith M. Lederer at the United Nations contributed.