A bomb exploded Wednesday evening outside a clothing store in a busy Colombo suburb, killing at least 16 people and wounding more than 20 others, the military said.

The blast occurred in the town of Nugegoda when a security guard outside a popular store became suspicious about a parcel and tried to open it, a defense official said, speaking on condition of anonymity because he was not authorized to speak to the media.

Earlier Wednesday, a handicapped suicide bomber sent by Tamil Tiger rebels to assassinate a Cabinet minister blew herself up at Sri Lanka's social services ministry in the heart of Colombo, killing a government employee, the military said.

The blast came hours after the rebels' top leader blamed the government for a recent escalation of fighting in the more than two-decade-old civil war that has killed an estimated 70,000 in the Indian Ocean island nation.

The suicide bombing targeted the offices of Douglas Devananda, the minister of social services and the leader of the Eelam People's Democratic Party, an ethnic Tamil party considered a rival to the separatist Tamil Tigers, the military said.

Devananda, the target of repeated assassination attempts, was not injured in the attack, the military said. The blast killed one of his staff members and injured two others, one critically, said Dr. Hector Weerasinghe, the medical director of Colombo National Hospital. The bomber was also killed.

The rebel group has been fighting since 1983 to create a separate homeland for Sri Lanka's minority Tamils following decades of discrimination by governments controlled by the Sinhalese majority.