Police were also stepping up checks on all vehicles entering the coastal district in the deep south of the island after fears that Tamil Tigers may smuggle explosives into the area for attacks, he said.
The heightened security came after Mahinda Rajapakse, the president, vowed to crush "terrorism" as his troops dismantled a de facto separate state run by Tamil Tigers in the island's east.
Rajapakse said the military had the strength to cope with the Liberation Tigers of Tamil Eelam (LTTE), which has been waging a decades-old campaign for independence.
"Terrorism that many once swore cannot be defeated is now crouching in fear because we faced up to that challenge," Rajapakse said.
"Our security forces have the ability, will and strength to defeat terrorism. Trust in them for they have proved it in the east [of the island]."
Government forces captured the main rebel bastion of Vakarai in the island's eastern district of Batticaloa on Friday, and the military said security forces were dismantling structures erected by the rebels.
Police are maintaining a high state of alert in and around the capital, Colombo, with several roads closed to traffic and parking restrictions across the city to prevent vehicle bomb attacks after a spate of blasts last year.