A Congolese policeman tries to stop displaced people entering an aid camp
British troops would be sent to boost the peacekeeping force in the DR Congo only as "a last case contingency provision," says minister Bill Rammell.
It would be "irresponsible" to rule it out but the immediate priority was ensuring the UN peacekeeping force was working effectively, he told MPs.
He stressed that the key to resolving violence was political.
Several Tory MPs said more UK troops should not be sent, owing to their commitments in Iraq and Afghanistan.
In the Commons earlier Foreign Office minister Mr Rammell was asked how many British troops might be deployed to the region.
He said: "We have made clear that is on the table as a last case contingency provision but were we to consider that, it is certainly not our immediate priority."
He told MPs: "It would be irresponsible to rule out contingencies given a very difficult situation.
"But all of our efforts and all of our statements have made clear that our overriding priority is that Monuc (the UN peacekeeping operation) operates effectively, that it is deployed effectively."
Former foreign secretary Sir Malcolm Rifkind warned him it would be "unwise to create expectations that can't be realised" adding: "The UK, given its other commitments in Afghanistan and elsewhere, is not in a position to make more than a purely symbolic contribution."
And Tory backbencher Bernard Jenkin said: "It really would be intolerable if British armed forces are called on once again, to stretch themselves even further when so few of our European allies are contributing significantly to current operations."
Liberal Democrat foreign affairs spokesman Edward Davey said it was right to be "cautious" about promising extra British troops "given the appalling overstretch suffered by our forces in Iraq and elsewhere".
But he said there was a strong case for Britain and the EU to "offer cash, know-how and logistical support to any reinforcements that African Union countries are prepared to offer."
And he emphasised the need for an economic, as well as political settlement, including "better control of the vast mineral resources that attract and fund these militias".
Hundreds of thousands of people have been displaced because of the violence in DR Congo's east region.
Both the Conservatives and the Liberal Democrats praised Foreign Secretary David Miliband for visiting the African country - he has been on a two-day visit with his French counterpart Bernard Kouchner.
Earlier Mr Miliband said the country needed foreign help to prevent further internal conflict and called on the rulers of DR Congo and neighbouring Rwanda to work together to form a "lasting solution"
He and Mr Kouchner held talks with the Congolese president, Joseph Kabila, and Rwanda's president Paul Kagama, urging them to use their influence and call and end to the fighting.
"The conflict in the east of the Democratic Republic of the Congo is not just a threat to regional stability but also has appalling human consequences," Mr Miliband said.
He described existing agreements between DR Congo and Rwanda as a "valid approach" to tackling the problems but added the African Union, United Nations and European Union all had to help restore peace.
Thousands of people forced to leave their homes are now in Goma
Rebel leader General Laurent 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 1994 Rwandan genocide.
But his forces, which are now believed to be based in the outskirts of the regional capital, Goma, have been accused of looting, rape and murder.
The Congolese government accuses Rwanda of backing the rebels, but both countries' presidents have agreed to attend a regional summit on the situation in the coming weeks.
Charities have estimated that more than 900,000 people have been displaced in the North Kivu province, where the capital Goma is situated.
Around 55,000 people are believed to have been forced to leave their home in the last week alone.
The United Nations has estimated that more than 1.6 million people are now displaced across the DR Congo.
Preparations to send out 90 tonnes of emergency government aid are now under way and thousands of blankets, plastic sheets, water buckets and water purification tablets expected to arrive in the region later this week.
Mr Miliband said that the UK had increased its aid funding to the region by £5m but did not discuss whether British troops would be sent to assist the UN peacekeeping force in the area.