UNITED NATIONS (AP) — The U.N.'s special representative for Congo said Wednesday the 19,000-strong U.N. peacekeeping force there is being stretched thin by multiple rebel militias in the eastern part of the country.

Roger Meece made the assessment in a live videoconference linkup to the Security Council from Kinshasa.

The council is assessing the performance of the MONUSCO peacekeeping force after 1,500 of its troops stood by Tuesday and let M23 rebels take the city of Goma without resistance.

U.N. helicopters over the weekend fired hundreds of rockets at the rebels in a bid to slow their advance on the city of 1 million.

But U.N. officials say the U.N. force commander in Goma ordered the peacekeepers not to shoot Tuesday in order to avoid provoking a major firefight in the city after Congolese troops retreated.

Meece said the M23 rebels were "well provisioned," uniformed and supplied with weapons, including night-vision goggles, that clearly came from some outside party.

He did not name the two countries that Congo has accused of aiding the M23 movement — Rwanda and Uganda.

Meece said investigation of that angle should be pursued by a U.N. group of experts whose report is due to be made public Friday.

Reports on a leaked early draft of the report say it contains accusations that Rwanda and Uganda have backed the M23 rebellion.

Uganda has threatened to pull its troops out of U.N. peacekeeping operations if that allegation is made public by the United Nations.

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(Photo: AP Photo/Marc Hofer)