Government forces launched fresh artillery attacks Sunday at a Tamil rebel-held reservoir that has been the focus of days of fighting.

The attack came hours after Tamil Tiger insurgents agreed to lift a blockade on water supplies to government-held villages, rebels and truce monitors said.

The artillery attack in the country's northeast began just as Ulf Henricsson, chief of a Nordic cease-fire monitoring team, and rebel officials were preparing to reopen the reservoir's sluice gates, rebel leader Seevarathnam Puleedevan told The Associated Press by telephone from Kilinochchi.

CountryWatch: Sri Lanka

Tommi Lekenmyr, chief of staff of the Sri Lanka Monitoring Mission in Colombo, confirmed that account, adding, "The sluice gates remain closed."

The rebels had agreed during talks with Norwegian peace envoy Jon Hanssen-Bauer to reopen the sluice gates they had closed two weeks ago — blocking water to 60,000 people in government-held villages, setting off government air strikes and ground assaults and plunging the island into its worst crisis in years.

Military spokesman, Col. Upali Rajapakse said that the military was firing artillery in the area to clear out rebel fighters.

"There is nothing new," he said of the artillery barrages.

The rebels said earlier that their decision to release water from the reservoir could be reversed if the government resumed airstrikes or attacks.

The Liberation Tigers of Tamil Eelam have fought for more than two decades to carve out a separate homeland for Sri Lanka's 3.2 million minority Tamils in the north and east.

A cease-fire put a temporary halt to the bloodshed, but the truce has nearly collapsed in recent months, and renewed fighting has killed more than 900 people — half of them civilians — since December, monitors say.

The water crisis dramatically escalated the violence, with six days of fighting around the northeastern port town of Trincomalee and the nearby town of Muttur.

Sri Lankan soldiers said Saturday they had re-established control over Muttur, and urged thousands of civilians displaced by the fighting to return home.