By David Loyn
International development correspondent, BBC News, DR Congo
UK Foreign Office Minister Lord Malloch Brown, who has special responsibility for Africa, has arrived in the Democratic Republic of Congo at the start of a four-day peace mission.
Gen Nkunda (r) agreed a ceasefire after meeting Mr Obasanjo (centre)
Speaking on his plane, Lord Malloch Brown told the BBC that if peace talks failed then there was the "prospect of ethnic conflagration on a very large scale going beyond the Congo into neighbouring countries".
The visit follows a new ceasefire agreed at the weekend by the Tutsi rebel leader in eastern DR Congo, Laurent Nkunda, after meeting the former Nigerian President Olusegun Obasanjo, who has been sent to the region as a peace envoy by the African Union.
Lord Malloch Brown said that the ceasefire and recent improved access for humanitarian convoys in eastern DR Congo were positive signs.
But a solution can only come when all sides carry out commitments previously made, particularly in the "Nairobi agreement".
The Nairobi Agreement, established in November 2007, called for foreign and domestic armed groups in eastern Congo to disarm.
Lord Malloch Brown said: "This really is about implementation, doing what everybody committed to do in those agreements, which they have absolutely not done.
"It's about dismantling the militias, it's about resettling them - some of them going home, others being resettled in different parts of the Congo."
The Tutsi rebellion in the east began in response to the failure of the disarmament process after a peace deal ending Africa's most bloody war was agreed in 2002.
Far from being disbanded and reintegrated into government forces, Hutu militias are still operating.
Some of the Hutu fighters now taking up arms again are believed to have been the same men who were responsible for the genocide in Rwanda in 1994 and have never been brought to justice - a source of continuing instability in the region.
The Nairobi agreement makes demands on a number of countries, in particular Rwanda and the Democratic Republic of Congo.
Britain is backing a resolution to increase UN peacekeepers
Few international observers believe Rwanda's President Paul Kagame when he says that he is not assisting Gen Nkunda's rebel force.
In order to increase security the UK might provide increased economic assistance to the disarmament process, as well as help to monitor the Rwandan border.
But it is unlikely that British troops would be sent to DR Congo for now, except to provide logistics.
There have been urgent calls from those running the existing UN peacekeeping force, Monuc, to increase its size, and Britain is now backing a new UN resolution to fund reinforcements.
But additional troops would initially be sought from countries who already have large troop contingents there, such as India and Pakistan, as well as African countries.
Battle for resources
In a worrying sign there have been several reports that Angolan troops are already on the ground -not as part of the international peacekeeping force but assisting government forces, raising fears that a regional war could break out again.
At the heart of the conflict is a battle for resources.
The Hutu militias have been profiting from gold and tin mines in the region, and a report by Global Witness earlier this year said that government forces have been assisting them.
The weakness and corruption of government forces puts soldiers from the international peacekeeping force in a difficult position, as they are supposed to be working alongside them.
But there are unlikely to be any changes in the mandate of the UN force. International donors, including Britain, are trying to improve the leadership and training of government forces to reduce abuses on the ground.
Lord Malloch Brown denied claims made by a pressure group in an advert in the Times newspaper in the UK that Britain was failing to carry out its duty to protect civilians by refusing to send its forces into the region.
He said it was "foolish and a red herring" to demand that the only solution was sending in British soldiers.