Sri Lanka's government said Monday it has no plans to withdraw from its cease-fire with Tamil Tiger rebels despite a regional Tiger leader declaring the accord dead because of an army assault on rebel territory.

The army forces in northeastern Trincomalee made slow progress in their assault, aimed at smashing a rebel blockade of water supplies, while the rebels opened a new front in clashes by shelling government troops in northern Jaffna Peninsula.

A Tiger leader in Trincomalee said the government was seeking to enter rebel territory, amounting to what he called a declaration of war. Under the country's 2002 cease-fire, the government and rebels must seek permission before entering each other's areas.

"Therefore for us the cease-fire is null and void," said Puratchi, who goes by one name.

Puratchi said he was speaking for the Tamil Tigers, but his comments could not immediately be confirmed by other rebel leaders. Top officials in the rebel stronghold of Kilinochchi were not available, said a person who answered the phone there.

The European team monitoring Sri Lanka's cease-fire declined to comment, saying the team had not yet received any official communication from the rebels.

The government said its assault in Trincomalee was aimed only at reaching a site where Tiger rebels were blocking a reservoir's flow of water to villages in government-held territory, and thus was not an act of war.

"Definitely not, we are not abrogating from the cease-fire," chief government spokesman Keheliya Rambukwella said.

"Our military's operation to open the irrigation gates is purely based on humanitarian grounds. It is not an act of war," he said.