War planes pounded the towns of Sorampattu and Palai, destroying mortar positions, the statement said.
But the pro-rebel Tamilnet.com said the military targeted civilian settlements in the north in land and aerial attacks.
On Thursday warplanes bombed Liberation Tigers of Tamil Eelam (LTTE) maritime bases in Chenmalai along the northern coast of the island, the defence ministry said.
"The Sea Tiger bases were completely destroyed," it added.
The Sri Lankan navy also said it had destroyed two suspected LTTE boats in the northwestern seas of Mannar carrying sacks of steel balls to make fragmentation mines.
There was no immediate comment from the LTTE.
The military offensive came a day after Britain's junior foreign minister said here his country was willing to play a bigger role in helping end Sri Lanka's long-running ethnic conflict, including direct talks with the LTTE.
"We'd be delighted to become more involved in helping to facilitate the peace process," Kim Howel