Kidnapped Norwegian freed in Yemen SANAA (Reuters) - A Norwegian working for the United Nations was freed on Friday, nearly two weeks after being kidnapped in the Yemeni capital Sanaa, the Interior Ministry said. A tribal source had said the Norwegian was abducted by tribesmen from oil-producing Maarib province demanding the release of a suspect accused of killing two members of the security forces. "He arrived in Sanaa and is in good health," an official at the U.N. office in Sanaa told Reuters. A UN statement said the man will return to his home country to recuperate. Lawlessness has gripped Yemen, one of the world's most impoverished countries, since mass protests calling for the end of President Ali Abdullah Saleh's 33-year rule began a year ago. One soldier was injured when unidentified militants attacked a security checkpoint in the port city of Aden late on Thursday. Saleh bowed to protesters' demands and is en route to the United States via Oman for medical treatment. He left behind a country facing numerous challenges, including a growing al Qaeda threat in the south. Washington and Yemen's oil-rich neighbor Saudi Arabia have long seen Saleh as a bulwark against the Islamist group's Yemen-based regional wing, which Washington believes is the network's most dangerous branch. A Houthi rebellion in the north and separatist sentiment in the country's south also pose challenges to a new government. Leaders of the Houthis and separatists said on Friday they would boycott the February presidential election meant to pull the country back from the brink of civil war. Thousands of protesters in at least two large southern cities demonstrated against the elections after noon prayers on Friday, some even burning their voting cards. "The people of the south reject the elections completely as (they) are not in the favor of the south," separatist leader Nasser al-Khubbagi told Reuters. Holding them is an affirmation of the (northern) occupation and legitimizes its continuation in the south. Residents told Reuters that the flag of the old southern Yemeni state, which had been an independent socialist nation before Saleh unified Yemen in 1994, appeared at the top of street lamps across the former state's capital Aden on Sunday. Separatist protesters waved the flags, differentiated from their Yemeni counterparts by a blue triangle encasing a red star on the right, while chanting: "These elections have nothing to do with us. The blood of southerners will not go to waste. The separatist movements leaders, including founder Nasser al-Nawba, vowed that the resistance to the elections would be non-violent. Reporting by Mohammed Ghobari and Mohammed Mukhashaf; Writing by Nour Merza; Editing by Robert Woodward