(Adds Rajapaksa advisor quits, fresh deaths)

By Simon Gardner

COLOMBO, Jan 6 (Reuters) - The Tamil Tigers' military intelligence chief was among 34 rebels killed in heavy fighting in northern Sri Lanka on Saturday, the military and a pro-Tiger Web site said, amid signs the 25-year civil war was escalating.

Colonel Charles was killed in clashes in the northwestern district of Mannar, where fierce fighting has been focused for months, the military said on Sunday.

The Liberation Tigers of Tamil Eelam (LTTE) had no immediate comment, but pro-rebel Web site www.tamilnet.com said Charles had been killed by a roadside bomb planted in Tiger territory by by an army deep penetration unit.

"It is confirmed that their military intelligence leader Charles was killed," said military spokesman Brigadier Udaya Nanayakkara.

The death comes just days after President Mahinda Rajapaksa's government announced it was formally cancelling a tattered 2002 truce with the Tigers. Analysts expect this to lead to a bloody intensification of a conflict that has killed around 70,000 people since 1983.

Just weeks ago the leader of the Tigers' political wing was killed in an air raid amid a declared government drive to annihilate the rebels militarily and overrun the de facto state they run in the island's north.

The military said troops killed another four rebels in the northern Jaffna peninsula on Sunday, and that two other Tigers committed suicide in the area by exploding a bomb to avoid arrest.

TRUCE MONITORS LEAVING

Nordic ceasefire monitors are wrapping up their six-year mission after the government gave 14 days notice last Wednesday that it was ending the ceasefire, which broke down on the ground almost as soon as Rajapaksa came to power in late 2005.

Well over 5,000 people have been killed since then in now near-daily air strikes, land and sea clashes and ambushes.

That means the gloves come fully off on Jan. 16.

The end of the truce dashes hopes of resurrecting collapsed peace talks any time soon.

Former Sri Lankan peace secretariat head Jayantha Dhanapala, who ran for UN Secretary General against Ban ki-Moon, quit on Sunday as Rajapaksa's senior advisor, citing personal reasons.

However, colleagues said he was keen to put distance between himself and Rajapaksa after he scrapped the ceasefire pact.

The government opted to cancel the truce after a series of deadly bombings blamed on the Tigers, who are fighting for an independent state in north and east Sri Lanka.

It argued that the insurgents, widely outlawed as a terrorist group, had used the pact to regroup and rearm, had violated the terms thousands of times and refused to talk peace sincerely.

The international community has expressed alarm at the government's decision, urging the state to reach a political settlement to the protracted conflict. Human rights groups are calling for a United Nations human rights monitoring mission in the wake of a series of abuses blamed on both sides. (Editing by Myra MacDonald)

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