Sri Lankan security forces have overrun three LTTE bases in the island's restive Trincomalee district in an offensive coinciding with the fifth anniversary of the ceasefire that is now practically holds only on paper.

Troops, backed by artillery, carried out a three-day operation to flush out guerrilla locations just north of Trincomalee on Friday, the Defence Ministry said.

"Troops are still continuing their search and clearing operations to provide safety and security for the civilians and troops," the ministry said in a statement.

Meanwhile, a pro-rebel website said troops were amassing heavy weapons along the de facto border in the island's north and there were long range attacks.

The LTTE rebels on Thursday announced the virtual collapse of a 2002 truce arranged by Norway and said military action by the island nation's government compelled them to achieve statehood.