UNITED NATIONS (CNN) -- The U.N. Security Council voted unanimously Thursday to send more than 3,000 additional troops to the Democratic Republic of Congo, bolstering a mission that is already its largest peacekeeping force in the world.
The resolution says the Security Council has "extreme concern at the deteriorating humanitarian situation and in particular the targeted attacks against civilian population, sexual violence, recruitment of child soldiers and summary executions."
But it did not extend the mandate of the U.N. peacekeeping mission in Congo, known as MONUC, which is due to expire at the end of the year.
The Security Council's move was a response to a request for more troops from the U.N. Secretary-General, Ban Ki-moon, international organizations including Human Rights Watch, and local human rights groups in Congo.
Sir John Sawers, the British permanent representative to the United Nations, said before the vote that it was a "matter of urgency" to get more peacekeepers to the Congo.
But he said that ending the conflict there required a political solution, not a military one, and emphasized that the primary role of U.N. troops would be to monitor any cease-fire agreed upon by the warring parties.
A coalition of 44 organizations in eastern Congo wrote to the Security Council on Tuesday, pleading for more troops urgently to support the 17,000 U.N. soldiers already there.
"This would help to prevent the atrocities that continue to be committed against civilians on an ever greater scale here in North Kivu, on the border of Rwanda and Uganda," the letter said. Watch efforts to avoid a health catastrophe in Congo »
Sawers said the U.N.'s peacekeeping department had been "taking soundings" from countries that might provide the additional 3,085 soldiers and police officers, and "a number of countries" were considering it, but he declined to name them.
Fighting between government forces, allied militias and rebels under the command of Laurent Nkunda has forced an estimated 250,000 people to flee their homes since August.
Aid organizations have warned that the huge African country is suffering a humanitarian disaster.
"Since August 28, fighting has intensified in many areas, causing deaths, rapes, lootings, forced recruitment and further displacements of civilian populations," the local charities wrote.
Their letter echoes concerns laid out by the British aid group Oxfam last week.
"The world is failing in its responsibility to protect the Congo's innocent civilians," Juliette Prodhan, the head of Oxfam in Congo, said in a statement released November 13.
"There has been an increase in incidents of forced labor, rape and widespread brutality, according to assessments carried out by international agency Oxfam over the past week, as armed men from all sides prey upon those who have sought 'sanctuary' from the fighting in North Kivu" province, she said.
Another aid group, World Vision, says the conflict in the DRC is the deadliest since World War II.
The country has been at war since 1997.
"The last decade of conflict has resulted in some 4 million deaths; an estimated 1,200 people die every day due to ongoing epidemics and war-related causes; some aid agencies estimate upward of 1,400 deaths per day," World Vision said in a news release.