Congolese soldiers fought rebels in the country's volatile east for hours Saturday, officials said, while a rocket landed inside the town of Goma and killed three people as border tensions escalated between Rwanda and Congo.

Scores of angry residents took to the streets of Goma in protest following several days of violence that has left at least seven dead and dozens wounded in this city of nearly a million near the Congo-Rwanda border.

Congo immediately blamed the rocket attack on neighbouring Rwanda, which has long been accused of supporting the eastern Congolese rebel movement known as M23.

"We wonder, for how long will the international community continue to tolerate these offenses?" Lambert Mende, a spokesman for the Congolese government, told The Associated Press.

Rwanda, which has vigorously denied allegations by the United Nations and others that it has provided support to the M23 rebels fighting the Congolese government, also accused Congolese forces of attacking Rwanda. The Rwandan army said mortar fire landed in several villages along the border Friday.

Brigadier Joseph Nzabamwita, a spokesman for Rwanda's military, said "acts of provocation that endanger the lives of Rwandan citizens will not remain unanswered indefinitely."

The M23 rebel group briefly took Goma last November and subsequent peace talks in neighbouring Uganda have repeatedly stalled. M23's leaders previously headed other rebel groups in the region that were backed by Rwanda. The rebel group is made up of hundreds of Congolese soldiers mostly from the Tutsi ethnic group who deserted the national army last year after accusing the government of failing to honour the terms of a deal signed in March 2009.

Congolese officials and the UN confirmed Friday that the new UN intervention brigade (UN Stabilisation Mission in the Democratic Republic of the Congo, or MONUSCO) had shelled rebel positions Thursday for the first time since the force was created in March.

Main roads through Goma were blocked early Saturday by burning tires and crowds chanting anti-MONUSCO slogans.

Martin Kobler, the UN mission chief, called on Goma residents to protect his staff after angry crowds tried to march on the mission headquarters there.

He said he understood people's impatience to see an end to rocket attacks, "but the UN are not the enemy."

Mineral-rich eastern Congo has been destabilised by a myriad of armed groups since the aftermath of Rwanda's 1994 genocide when Hutu extremists blamed for the bloodshed fled to Congo.