The crisis appeal's chief executive, Brendan Gormley, said aid was getting through but a massive scale-up was needed.
"The start of the rainy season has meant people living in already desperate conditions are becoming ever more vulnerable," he said.
"Our member agencies are already reaching several hundred thousand people, but the need is overwhelming and increasing."
He said it was easy to donate and that £30 would pay for basic clothes for a child and provide assistance when he or she was reunited with family. A £50 donation would fund medical assistance for a rape victim.
"These aren't big sums. I know life is tough at the moment but with modest sums we can make a real difference," he added.
Orphaned children
Clashes between the army and the rebel forces of Gen Nkunda in eastern DR Congo have driven several hundred thousand people from their homes and created a humanitarian crisis.
The United Nations Security Council has responded by voting to send 3,000 more soldiers to the country.
It means the UN peacekeeping force Monuc will now consist of around 20,000 troops and police - the biggest of its kind.
Charles Badenoch, chief executive of the committee's member agency World Vision, said: "Children are being separated and orphaned by this intense conflict.
"Thousands of people are vulnerable to rape, malnutrition, abduction and disease. We urgently need your help to bring them relief, stability and hope."
Aid workers on the ground say many people have been displaced by the conflict for the second, third or fourth time.
They also said around 5,500 former child soldiers living in camps are vulnerable to being re-recruited by the warring militias.
In the town of Kanyabayonga, the charity Oxfam said there has been a 10-fold increase in rapes reported at local hospitals and clinics in the last six months.
Child malnourishment is also on the rise, World Vision said.
Donations can be made by visiting www.dec.org.uk or calling the DEC on 0370 60 60 900 or at any High Street bank or post office.
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