Military officials said the air force was called in to bomb suspected Tiger "strong points" around Kilinochchi.
Security forces carried out simultaneous ground attacks against Tamil Tiger defences around Kilinochchi and on the Jaffna peninsula on Tuesday, the defence ministry said.
In a rare statement announcing casualty figures, the ministry said 25 troops had been killed, with another 10 missing and 160 wounded, while an estimated 120 Tigers were killed and 250 wounded.
For their part, the rebel Liberation Tigers of Tamil Eelam (LTTE) said they had repelled the multi-pronged offensive by government forces, killing 170 soldiers and wounding 420.
The pro-rebel Tamilnet website quoted Tiger official S. Puleedevan as saying they had killed 130 soldiers outside Kilinochchi while another 40 were killed on the nearby Jaffna peninsula.
The Tigers s