(Updates with Tiger mourning period) COLOMBO, Dec 15 (Reuters) - Shadowy Sri Lankan rebel leader Velupillai Prabhakaran on Friday mourned his chief negotiator, ideologue and best friend, saying his death was an irreplaceable loss as the group intensifies its fight for independence. Anton Balasingham, who steered the rebels through many rounds of abortive peace talks with the Sri Lankan state and clinched a 2002 truce that now lies in tatters, died of bile duct cancer in London on Thursday aged 68. "His death comes at a time when we needed him most, as our freedom struggle intensifies," Prabhakaran said in a statement emailed to Reuters. "He was the central figure in all our diplomatic efforts." "I am proud to bestow the title of 'Voice of the Nation' on Bala Annai ... The yearning of the Tigers is Tamil Eelam," he added, referring to a homeland for minority Tamils in north and east Sri Lanka the Tigers are fighting to establish. Balasingham was a trusted confidant of Prabhakaran and wrote his speeches, and his death comes amid a deadly new chapter in the island's two-decade civil war. The Tigers on Friday declared three days of mourning until Sunday, but shot down reports they were considering a unilateral ceasefire during the period. But it was not immediately clear when or where Balasingham's funeral would take place. Balasingham, who had a doctorate in social sciences and became a British national after working at the British High Commission in Colombo, spearheaded successive rounds of peace negotiations for the Tigers from 1985. He had lived in Britain since a 1999 kidney transplant, and announced last month he was suffering from bile duct cancer. Analysts say Balasingham's death has deprived the rebels of an experienced negotiator who had a wide view of the conflict, and could well hamper efforts to revive the island's peace process, which has collapsed into renewed war. In March, Balasingham told Reuters the Tigers would push for an independent state unless President Mahinda Rajapakse agreed to wide autonomy for the island's minority Tamils. "Unless Rajapakse ... accepts the demand of the Tamils for regional autonomy, there won't be any prospect for a political solution," he said at the time. "If ... internal self-determination is rejected, then only we will invoke the right to external self-determination -- that is the right to form an independent state." Last month Prabhakaran declared the Tigers were resuming their fight for independence, which analysts said meant the renewed civil war would intensify. More than 3,000 troops, civilians and Tiger fighters have been killed so far this year in ambushes, military clashes and suicide bombings, taking the death toll from the conflict to more than 67,000 since it erupted in 1983.
