BANGKOK - A smoke bomb exploded late Monday outside the offices of the People Power Party in Bangkok, but caused no injuries and only minor damage, party officials said.

A grenade was also found lodged in the gate to the party's office on the northern side of the Thai capital, and police were working to defuse it, said Boontrika Prasongdee, a local politician with the party.

"There was an explosion at 9:00 pm (1400 GMT). It was a smoke bomb, which exploded and made a lot of smoke. A second bomb is still lodged at the front gate and has not exploded," she said.

The office was empty when the smoke bomb went off and no one was injured, she added.

Police could not be reached for comment, and Boontrika said she had no idea who might have set the bomb.

The blast came as Thailand gears up for general elections Sunday, the first polls since prime minister Thaksin Shinawatra was ousted in a coup last year.

Thaksin is living in exile in Britain and his party has been disbanded, but his allies have regrouped under the People Power banner and are the frontrunners in the election.

- AFP /ls