Ban Ki-moon said the conflict had 'catastrophic consequences'
UN Secretary-General Ban Ki-moon has said he will travel to East Africa to push forward efforts at ending the ongoing crisis in eastern DR Congo.
Mr Ban decried the "catastrophic consequences" of the conflict along the Rwandan-Congolese border.
Recent fighting in the area between government and rebel forces has forced 250,000 people from their homes.
Earlier, the French foreign minister called for the mandate of UN troops in DR Congo to be strengthened.
UN peacekeeping chief Alain Le Roy, visiting the town of Goma surrounded by rebel forces, said the UN mandate was currently to "protect civilians and to support the army in disarming rebel forces".
"Our mandate is not to defend cities," he told the BBC's Network Africa programme.
On Monday, a first UN convoy carrying medical supplies was given safe passage into rebel-held territory, where aid agencies have described the humanitarian situation as dire.
During his planned visit this weekend, Mr Ban plans to hold talks with both Congolese President Joseph Kabila and Rwandan President Paul Kagame.
"The conflict along the Rwanda and Congolese border has gone on too long and [with] catastrophic consequences," he said.
The UN chief has also named former Nigerian President Olusegun Obasanjo as his special envoy to the region.
The BBC's Peter Greste in DR Congo says the country has not seen this level of international attention for years - which is one reason why its conflict has been simmering for so long.
French Foreign Minister Bernard Kouchner has called for both the mandate and the numbers of the UN force in DR Congo - Monuc - to be beefed up.
"We need different soldiers, and different rules of engagement," he said after briefing his EU counterparts about a weekend visit to the region.
Rebels who routed the army in the eastern North Kivu province last week now control large swathes of land around the regional capital, Goma.
But a spokesman for the rebel leader, renegade General Laurent Nkunda, said the Congolese government was "waging war" by refusing to hold direct negotiations.
The government has long rejected one-to-one talks with the rebels, saying he should stick to a peace deal signed in January.
Monuc, which has 17,000 troops in the country, is the biggest UN peacekeeping mission in the world, but is struggling to contain the conflict.
Mr Le Roy said he hoped the UN Security Council would listen to a request made a month ago to increase the UN troops.
For now, Monuc's priority was to reinforce itself in North Kivu.
"Our priority is Goma - to make sure Goma is a red line," he said.
"Then we strengthen our presence on the road between Goma and Rutshuru to make sure there is clear access to humanitarian goods."
Following a meeting of EU foreign ministers in France on Monday, Mr Kouchner said the force needed "more of an offensive capability".
He said the peacekeepers' rules of engagement were "insufficient" and "very restrictive", and did not rule out sending EU troops to DR Congo as well.
Mr Kouchner and his British counterpart David Miliband travelled to DR Congo and Rwanda at the weekend.
UN troops escorted Monday's aid convoy to Rutshuru, a rebel-held town 75km (45 miles) north of Goma.
It carried medical supplies and water purification tablets, and the UN said food convoys were expected to follow.
Aid workers found refugee camps that had held tens of thousands were virtually empty. Many people are believed to have fled into the forests around the camps fearing further violence.
While as many as 50,000 displaced people reached Goma, many others have tried to return to their homes on foot without safe shelter, food or water.
The recent rebel offensive was exacerbated by a wave of killing, looting and raping by retreating Congolese soldiers.
Meanwhile, the Associated Press news agency quoted a UN official as saying that Rwandan forces fired tank shells into DR Congo during last week's fighting.
Rwandan officials had denied the allegations, spokeswoman Sylvie van den Wildenberg said, "but we saw it. We observed it."
If confirmed, it would be the first time the UN has publicly accused Kigali of being overtly involved in the conflict.
Although Rwanda has twice invaded its much larger neighbour in recent years, it has repeatedly denied accusations its forces were actively supporting Gen Nkunda.
UK Prime Minister Gordon Brown has said the international community must "not allow Congo to become another Rwanda".
In 1994, 800,000 people died in Rwanda's genocide, which is seen as the origin of the current conflict across the border.
Gen Nkunda says he is fighting to protect his Tutsi community from attack by Rwandan Hutu rebels, some of whom are accused of taking part in the genocide.
There have also been accusations of collusion between DR Congo's army and Hutu guerrillas.