Eastern Congo clashes feed tensions with Rwanda MUJA, Democratic Republic of Congo (Reuters) - The Congolese army shelled rebel positions near the eastern town of Goma on Monday in a second day of fierce fighting that led to rivals Rwanda and Congo trading accusations of aggression. The United Nations, which is deploying a 3,000-strong Intervention Brigade with a mandate to enforce peace in eastern Democratic Republic of Congo, vowed to halt any rebel advance towards Goma. The worst fighting for several weeks prompted Kinshasa to repeat claims that Rwanda was backing the Tutsi-led M23 rebels. Rwanda, meanwhile, accused Congolese and U.N. troops of deliberately shelling its territory. The escalating tension underlines the challenge facing the U.N. Brigade - drawn from South Africa, Tanzania and Malawi - as it seeks to end unrest in eastern Congo in which millions of people have died from violence, hunger and disease since the 1990s. At Muja, a village some 11 km (7 miles) from Goma, government forces used heavy weapons to try to drive back M23 fighters after clashes on Sunday afternoon. "We are going to chase the enemy very far from Goma so that they will not have a chance to recapture the town," army spokesman Colonel Olivier Hamuli told Reuters television. The M23 rebels alarmed many countries in November by seizing Goma, a city of 1 million people on the shore of Lake Kivu. The rebel takeover sparked widespread criticism of U.N. peacekeeping, prompting a drive for a regional peace deal and the creation of the new brigade. Fighting resumed at 5.30 a.m. (11:30 p.m. ET) on Monday after calm overnight, Hamuli said. The U.N. peacekeeping mission in Congo said on its Twitter feed that it would use "all means necessary" to protect civilians and that any rebel push towards Goma would be seen as a direct threat to civilians. In Kinshasa, government spokesman Lambert Mende accused Rwanda of backing the M23 in fighting and said the rebels had sustained heavy losses in Sunday's combat. In army ranks, we lost 10 of our valiant fighters. Both sides in the conflict routinely inflate enemy casualty figures. An army official on the ground in eastern Congo said it was too early to give a precise estimate. M23 spokesman Vianey Kazarama said rebels held the upper hand and would resist until the government offensive ended. The 17,000-strong U.N. force in Congo (MONUSCO), the world's largest peacekeeping mission, has been deployed for more than a decade but has failed to stem the complex conflict. The arrival of the Intervention Brigade - part of MONUSCO but with a more robust mandate - which has begun patrolling and is approaching full strength, has raised some hopes of peace. The World Bank is offering $1 billion to regional governments to promote development if they respect a U.N.-brokered February deal not to back rebels in Congo. Subsequent talks between the Congolese government and M23 in Kampala, the capital of neighboring Uganda, have stalled. Congo has long accused Rwanda of backing the M23. A U.N. panel of experts' report said the group recruits in Rwanda with the aid of sympathetic military officers. Kigali, which has in the past backed insurgents in Congo, denies any support for M23. Rwanda's military on Monday accused the Congolese army (FARDC) and U.N. troops of bombing Rwandan territory though it said no one was hurt. "This was a provocative and deliberate act by FARDC and MONUSCO since there was no fighting nearby between the warring factions," a spokesman for Rwanda's military said. Separately, in a letter to U.N. diplomats seen by Reuters on Monday, Rwanda accused the intervention brigade of discussing collaboration with the FDLR, a group of Hutu rebels linked to the Rwandan genocide of 1994, in order to take on M23. Additional reporting by Bienvenu-Marie Bakumanya in Kinshasa and Edmund Kagire in Kigali; Writing by Daniel Flynn and David Lewis; Editing by Robin Pomeroy