* Congo army drove M23 rebels from positions
* Victories a chance to push political solutions - envoy
* Strong perception Rwanda backing rebels - Robinson
The U.N. special envoy for Africa's Great Lakes region said on Monday recent military successes by Congo's army against eastern rebels should be used to relaunch peace talks.
Democratic Republic of Congo's army drove M23 rebels from positions overlooking the eastern city of Goma on Friday, scoring its biggest victory since the uprising began 18 months ago.
"When there is a military victory like this, it is a chance to advance with a political solution, and that is better for a durable peace," said envoy Mary Robinson, a former Irish prime minister, without going into further details.
The military breakthrough came after a new U.N. intervention brigade, with a tough mandate to crush armed groups, entered combat for the first time. U.N. artillery and helicopters pounded M23 positions in Kabati, 11 km north of Goma, until rebels withdrew.
Millions of people have died from violence, disease and hunger since the 1990s as foreign-backed ethnic rebel groups have fought for control of eastern Congo's rich deposits of gold, diamonds and tin, destabilising the Great Lakes region.
Congo opened peace talks in Kampala, the capital of neighbouring Uganda, after the rebels briefly seized Goma in late 2012, but the negotiations quickly stalled.
"This time it must be different. At the international level we are engaged more than ever before," Robinson said.
She is visiting the vast, former Belgian colony as part of an international mission including the United States special envoy for the Great Lakes region, Russ Feingold, and the special representative of the African Union, Boubacar Diarra.
Regional leaders will meet in Kampala on Thursday to discuss Congo, with world powers increasing pressure for a solution.
U.N. Secretary General Ban Ki-moon visited the region in May, offering $1 billion in World Bank funding if nations stuck to a February deal not to support rebels on each others' soil.
Robinson noted there was evidence that the Tutsi-dominated government in neighbouring Rwanda was supporting M23, whose leaders come from the same ethnic group. In 2012, U.N. investigators accused Rwanda of backing the rebels, a charge Rwanda has denied.
"There is a strong perception (Rwanda is supporting M23), there seems to be some evidence for that," said Robinson. "This is having an impact on how donor countries perceive the situation."
M23 took up arms accusing Congo's government of failing to honour the terms of a 2009 peace deal that ended four years of Tutsi rebellion in the east. It accuses Kinshasa of backing Hutu militia linked to the 1994 genocide in Rwanda.
Robinson said she supported the military action by the Congolese army and the new 3,000-strong U.N. Brigade, which intervened directly for the first time on Aug. 23 after rebel shells landed in Goma, killing at least three civilians.
"Sometimes a military engagement is necessary to protect the population," she said in Goma, a lakeside city of one million on Congo's border with Rwanda.
During nearly two weeks of fighting, rockets have also landed in Rwanda, killing civilians.
The government in Kigali warned it would not tolerate such "provocation", raising fears it could intervene directly in eastern Congo - where it has fought two wars in the last two decades under the pretext of hunting down Hutu militia.
Congolese army spokesman Lt Colonel Olivier Hamuli said on Monday the front had been calm for the past two days.
"We must consolidate our positions," he said.