COLOMBO, May 28 (Xinhua) -- Seven civilians were killed and 33 others including four soldiers were injured Monday afternoon in an explosion in the southern suburb of the Sri Lankan capital Colombo, defense officials said.

    A Claymore mine exploded at about 5:40 p.m. (1210 GMT) targeting a truck with nine personnel of police Special Task Force(STF) onboard near a book shop in Ratmalana, about 15 km south of downtown Colombo, said military spokesman Prasad Samarasinghe.

    The dead were from the 36 civilians initially injured in the explosion, officials from the Media Center for National Security said, adding that three of the dead were females and four of them males.

    Samarasinghe accused the Liberation Tigers of Tamil Eelam(LTTE) for the attack with civilians being clearly targeted.

    The injured have been rushed to nearby hospitals, police said.

    Sri Lankan President Mahinda Rajapakse has condemned the attack on the civilians, the state television reported.

    The truck was proceeding on the main Colombo-Galle road when the Claymore mine tied on the roof of a roadside house went off, officials said.

    Several shops and vehicles were also damaged in the explosion.

    This is the second attack on military targets in the capital area within a week.

    One soldier was killed and six people including three civilians were injured in a Claymore mine attack carried out by suspected LTTE rebels in Colombo on Thursday.

    Clashes between government troops and LTTE rebels are now an almost daily occurrence in the island country.

    About 5,000 soldiers, rebels and civilians have been killed since December 2005 despite the Norwegian-arranged truce in place.

    Claiming discrimination at the hands of the majority ethnic Sinhalese-dominated government, the LTTE has been fighting for an independent homeland for Sri Lanka's 12.5 percent Tamil minority since the 1970s.