Tamil rebels are seeking an independent homeland for the ethnic Tamil minority in the Sinhalese-majority nation.
Warplanes also bombed rebel targets in northern Manner district, the defence ministry said, adding that the mission on Wednesday was successful.
There was no word on casualties nor immediate comment from the Tamil Tigers.
Soldiers on foot patrols fired at a group of Tiger rebels in eastern Trincomalee district Tuesday, killing two guerrillas, military officials said.
Another suspected rebel blew himself up to avoid being captured in the northern district of Vavuniya also on Tuesday, officials said, adding that troops found a dead body of an unidentified person in the same district.
The pro-rebel Tamilnet.com website said two civilians had been shot dead in Vavuniya on Tuesday.
In separate violence, two Sri Lankan soldiers were wounded in Vavuniya on Wednesday, when they stepped on a roadside mine, the website said.
The violence came as John Holmes, UN undersecret