"We're treating people with arms and legs blown-off by grenades and other heavy arms," said Wieland. He also said that for the first time they treated many more civilians than combatants.
He said that since April, Doctors Without Borders has treated more than 500 people hurt in the conflict.
Congo's army now controls only the city of Goma and the village of Kibumba, six miles outside Goma. Now the rebels hold all towns going north as far as Rutshuru and are threatening to besiege Goma.
The U.N. Security Council on Thursday demanded that the M23 rebel group halt any advances toward Goma. In a statement delivered by council president Gerard Araud of France, the Security Council expressed deep concern at the worsening humanitarian situation, especially the increasing number of refugees, and called on the international community to provide appropriate humanitarian support.
The Security Council reiterated its strong condemnation of any and all outside support to M23.
Neighboring Rwanda has been accused of supporting the rebels in the mineral-rich territory, which the Rwandan government has emphatically denied.
Uganda's foreign affairs minister said on Friday that his country's forces are not fighting in the Congo and that Uganda's president is actively trying to help resolve the conflict there.
Okello Oryem told reporters in Kampala, Uganda's capital, that allegations of Uganda's military involvement in the Congo are "rubbish." President Yoweri Museveni visited Angola this week to consult with officials on how best to find a regional solution to the Congo violence, Oryem said.
Col. Felix Kulayigye, the spokesman for the Ugandan military, told The Associated Press on Wednesday that the Ugandan government is investigating reports that some M23 rebels were seen wearing Ugandan army fatigues and that a rebel commander uses a vehicle with a number plate associated with the Ugandan army.
"Some of the rebels are putting on our uniform," Kulayigye said. "It seems there is a scheme intended to soil Uganda's image."
Next week Uganda will host a conference on regional security that President Paul Kagame of Rwanda and President Joseph Kabila of Congo are expected to attend.
Valerie Amos, the U.N. Under-Secretary-General for Humanitarian Affairs and Emergency Relief Coordinator, is scheduled to visit Congo and Rwanda next week to "draw attention to the deteriorating humanitarian situation," the U.N. said Friday.