(Updates with government comment)

COLOMBO, Jan 8 (Reuters) - A bomb exploded in a phone booth in a block of flats in the business area of the Sri Lankan capital on Tuesday evening, but there were no immediate reports of any casualties, the government said.

The blast came hours after suspected Tamil Tiger rebels killed a government minister with a roadside bomb between Colombo and the island's international airport.

"It was an explosive. They have put a bomb inside a telephone booth in a block in Regent's flats," said Lakshman Hulugalle, director general of the Media Centre for National Security, referring to a building on a roundabout near the Hilton hotel in the city's business district.

There has been a series of attacks on government officials and the military in recent months, and Tuesday's violence comes just days after the government said it was formally scrapping a tattered ceasefire which degenerated into renewed civil war in early 2006.

"So far there are no casualties or any damages," Hulugalle added. "Definitely it is the work of the Tamil Tigers."

The Liberation Tigers of Tamil Eelam (LTTE), who want to carve out an independent state in north and east Sri Lanka, were not immediately available for comment, but routinely deny involvement in attacks.

The government has vowed to wipe out the Tigers militarily, setting the stage for what many fear will be a bloody battle for the north as a death toll of around 70,000 people since the war erupted in 1983 climbs daily. (Writing by Simon Gardner, Editing by Matthew Jones)

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