All vehicles entering Colombo were searched by heavily-armed troops and police during a three-hour period, a police spokesman said.

The move, following a blast Monday evening at the edge of the capital, which claimed at least eight lives, caused huge traffic jams in the morning.

Just before the search got underway Tuesday, another blast in the island's north killed three people.

"All vehicles entering the city were checked," a police spokesman said. "This was a precautionary measure after yesterday's bomb attack."

A police commando wounded in Monday's bomb attack died of his injuries Tuesday, raising to eight the number of people killed in that attack at Ratmalana, near a major airbase.