* UN chief Ban asked to report on rebel external support
* Rwanda, Uganda deny backing eastern Congo rebellion
* UN says peacekeepers no substitute for Congolese army
By Michelle Nichols
UNITED NATIONS, Nov 20 (Reuters) - The U.N. Security Council strongly condemned M23 rebels in eastern Democratic Republic of Congo on Tuesday for seizing a provincial capital, as the United Nations defended its peacekeepers who gave up the battle for the city of Goma.
The 15-member council unanimously adopted a resolution that also requested that U.N. Secretary-General Ban Ki-moon "report in the coming days" on allegations of external support for M23, upon which it would be ready to take further measures.
M23 fighters, who U.N. experts say are backed by neighboring Rwanda and aided by Uganda, entered Goma on Tuesday following days of clashes with U.N.-backed Congolese soldiers that forced tens of thousands of residents to flee.
Rwanda and Uganda have repeatedly denied the allegations made by the Security Council's Group of Experts in a confidential report, which was seen by Reuters last month.
The council expressed "deep concern at reports indicating that external support continues to be provided to the M23, including through troop reinforcement, tactical advice and the supply of equipment, causing a significant increase of the military abilities of the M23, and demands that any and all outside support to the M23 cease immediately."
It demanded "the immediate withdrawal of the M23 from Goma, the cessation of any further advances by the M23 and that its members immediately and permanently disband and lay down arms."
The Security Council also said it was ready to consider additional targeted sanctions against the leadership of M23 and also those providing external support for M23 and violating an arms embargo on the Democratic Republic of Congo.
The U.N. experts group last week recommended sanctions be imposed on Rwandan Defense Minister James Kabarebe, who it has accused of commanding the M23 rebellion, and other Rwandan officials, diplomats said. The committee took no action on the Rwandans, but did designate M23 leader Sultani Makenga for sanctions.
PEACEKEEPERS NO ARMY SUBSTITUTE
Human Rights Watch was disappointed that the Security Council had not named Rwanda for sanctions in Tuesday's resolution and called on the United States, which has protected Kigali on the council, to support stronger action.
"If the Security Council is to protect civilians in Goma, it needs to send a clearer message to Kigali," said Human Rights Watch United Nations director Philippe Bolopion. "For the sake of Goma's population, the U.S. should support urgent sanctions against the M23's foreign backers."
U.S. State Department spokeswoman Victoria Nuland said in a statement that the United States "demands that any and all outside support and supplying of equipment to the M23 cease immediately."
A senior U.N. source told Reuters that the peacekeepers gave up defending Goma, a frontier city of about 1 million people, on Tuesday after the Congolese troops evacuated under pressure from the advancing rebels.
"MONUSCO (the U.N. mission in Congo), of course, cannot substitute for the efforts of national security forces including the FARDC (Congo national army)," said Eduardo del Buey, U.N. Secretary-General Ban Ki-moon's spokesman.
Del Buey said there were about 1,500 peacekeepers in Goma who would stay "to protect civilians from imminent threat." About 170 non-essential U.N. staff left Goma on Tuesday and more were due to be relocated on Wednesday.
"Reports indicate that the M23 has wounded civilians, is continuing abductions of children and women, is destroying property and is intimidating journalists and those who have attempted to resist their control," Del Buey said.