Security forces seized territory that had been held by the Liberation Tigers of Tamil Eelam (LTTE) just south of Mannar in the northwest of the island nation on Saturday, military officials said.
"The army is now engaged in consolidation operations to retain control of the area," the defence ministry said in a statement.
The LTTE in a statement said nine people were killed and four injured in a landmine blast caused by Sri Lankan troops during the fighting.
The defence ministry however accused the LTTE of attacking civilians for allegedly trying to enter government-held parts of the Mannar.
The LTTE also said Sunday that they killed a government soldier and lost one of their men in Saturday's fighting. The defence ministry said intercepts of rebel radio communications indicated that 11 guerrillas were killed.
Both sides regularly make casualty claims that cannot be independently verified.
Government forces have been trying to break into rebel-held territory in the Mannar di