Congo's U.N. peacekeeping mission struggled on Sunday to impose a temporary ceasefire as fighting between government forces and Tutsi rebels neared an eastern city, a U.N. spokesman said, Reuters reported. Government forces attacked rebel positions with heavy guns and mortars in two locations on Sunday, rebels said in a statement, although there was no independent confirmation. Rebels in hillside positions traded heavy gun and mortar fire with government soldiers below early on Saturday in the town of Sake, 25 km (16 miles) from Goma, strategic capital of troubled North Kivu province. U.N. troops, based in Sake to monitor the town since a failed government offensive against the insurgents last December, were caught in the crossfire. "We will not let the (rebels) take Sake," MONUC's military spokesman Lieutenant-Colonel Jean-Paul Dietrich said on Sunday. "There is still no solution. There isn't yet a ceasefire. But at least they aren't shooting at each other right now." Sake is located on one of two main roads leading out of Goma and just a few kilometres from camps containing tens of thousands of North Kivu's internal refugees. Congo's peacekeeping mission, known as MONUC, has repeatedly vowed to keep the town from falling into the hands of the rebels, led by renegade Tutsi General Laurent Nkunda. Dietrich said MONUC failed to negotiate a temporary halt to fighting in Sake on Saturday, as thousands of civilians fled.