By Elias Biryabarema

KAMPALA (Reuters) - Congolese rebels declared a unilateral ceasefire on Tuesday ahead of a second round of peace talks with the government, boosting hopes for a negotiated end to their nine-month-old revolt.

The M23 insurgents had already agreed to pull out of Democratic Republic of Congo's eastern city of Goma last month - but a first round of negotiations that followed that withdrawal fell apart amid threats and accusations.

"We've been for peace ... Today we're declaring that we're in a ceasefire ... Even if the government refuses to sign a ceasefire agreement we'll continue with the negotiations," Francois Rucogoza, the rebels' executive secretary told a journalists in Uganda's capital Kampala, speaking through a translator.

The announcement marked a relaxation of the rebels' demand last week that the government also sign a ceasefire before talks resumed.

Foreign powers fear the conflict could spark another regional war in a borderlands zone that has suffered nearly two decades of turmoil. Neighboring Uganda and Rwanda are accused by a group of U.N. experts of supporting the rebel campaign, a charge both countries deny.

At first, M23, named after a 2009 peace deal for eastern Congo, said it had taken up arms because the Kinshasa government failed to honor its side of the bargain, under which rebel fighters were integrated into the army. It later broadened its goals to include the "liberation" of all of Congo and the removal of President Joseph Kabila.

(Additional reporting by George Obulutsa; Writing by James Macharia; Editing by Andrew Heavens)