New Delhi, Dec. 22 -- The U.N. Security Council has urged Rwanda to withdraw its forces from eastern Congo and extended the U.N. peacekeeping mission in Congo, known as MONUSCO, for a year, as fighting in the region escalated despite a U.S.-mediated peace deal.

The U.N.'s most powerful body on Friday condemned an offensive by the Rwanda-backed M23, demanded Rwanda stop supporting the rebels and withdraw its troops. The Security Council also renewed the peacekeepers' mandate, keeping about 11,500 military personnel in the country, in a unanimously adopted resolution.

The resolution comes as M23 claimed Wednesday to have withdrawn from Uvira, a strategic city in eastern Congo it seized last week, after pressure from the U.S. Congo's gover...