Heavy fighting has taken place between government and rebel forces in eastern Democratic Republic of Congo.These are the first clashes between the two sides since the rebels pulled out of the regional capital, Goma, last year.They come after the UN began deploying an attack force to the area last week.Meanwhile, Rwandan President Paul Kagame told the BBC that UN troops had "in some cases" made the situation in DR Congo worse.The UN has nearly 20,000 peacekeepers in eastern DR Congo, where armed groups have wreaked havoc for two decades.'No plan to advance'The BBC's Maud Jullien in the capital, Kinshasa, says the government believes the M23 is trying to disrupt the deployment of the UN force.North Kivu provincial governor Julien Paluku told the BBC that security was being increased in Goma, as he feared the rebels would try to cut the city off from the provincial army headquarters in Bueremana.He said rebel fighters from across the province were taking part in this offensive.M23 rebels attacked government troops about 12 km (7 miles) north of Goma, said army spokesman Olivier Hamuli.The army pushed back the rebels after two hours of heavy fighting, but sporadic clashes were continuing, he added.But the M23 accused government troops of attacking them first.It repelled the offensive and captured key positions overlooking Goma, said M23 spokesman Viannay Kazarama.The M23 was not planning to advance towards the city, he added.Some 800,000 people have fled fighting since the M23 launched its rebellion last year.This led the UN to deploy a new 3,000-strong intervention brigade to eastern DR Congo to neutralise and disarm the rebels.The first contingent of the force arrived last week.UN officials say the force, made up of troops from Tanzania, Malawi and South Africa, had the most robust mandate ever given to a UN mission to end instability caused by rebel groups.Our correspondent says the M23 has been hit by a wave of defections since the UN Security Council adopted a resolution in March to send the force.One defector told the BBC earlier this month that the M23 had drawn up plans to disrupt the deployment by cutting off one of the main roads to Goma.In an interview with the BBC, Rwanda's leader said any military effort to bring peace to DR Congo needed to be "properly co-ordinated" with political efforts.He dismissed long-standing UN allegations that Rwanda backed the M23.Asked how he viewed the record of the UN force, Mr Kagame said: "If you see what we had last year, the resurgence of the fighting and chaos and displacement of people and so on and so forth... what we witnessed last year - actually the situation got worse."Rwanda was accused of backing armed groups in DR Congo as a way to fight Hutu rebels who fled there after the 1994 Rwandan genocide.Mr Kagame came to power as the head of a Tutsi rebel force, which ousted the genocidal Hutu leadership.