Sri Lanka has in the past accused international diplomats raising rights concerns as "terrorists" and supporters of the Tigers, who are waging a decades-old battle for an independent homeland for the island's Tamils.
Heavy fighting along the de facto border separating territory held by the Liberation Tigers of Tamil Eelam (LTTE) saw fierce clashes on Wednesday and Thursday, leaving a total of 47 combatants killed, the ministry said.
It said security forces had captured key locations from the Tigers in the coastal district of Mannar over the past two days.
In a bomb attack inside rebel-held territory on Thursday, a pro-rebel Tamil lawmaker and his driver were killed, officials said.
The Tigers accused the security forces of carrying out the attack.
So far this year, the defence ministry has reported that security forces have killed at least 1,882 rebels with the loss of 112 government soldiers.
The government numbers cannot be independently confirmed as Colombo allows no access by