BANGKOK ? A grenade exploded early Friday on a street in central Bangkok, leaving one person seriously hurt in the latest violence in the Thai capital, still recovering from deadly protests, officials said.

The grenade was put in a plastic rubbish bag and dropped in Rangnam road near a duty-free shopping centre, police said. The injured person was a Thai man in his 30s who was searching for scrap.

"It was a hand grenade... The pin was removed and a rubber band wrapped around it," Police Major General Vichai Sangparpai told local television.

The unnamed victim was seriously hurt and still in hospital, according to Bangkok's Erawan emergency center.

"His condition is serious as he sustained wounds all over his body," an Erawan official said.

The blast came less than a week after a small bomb exploded at a Bangkok bus stop, killing one person and injuring 10 in an attack that rekindled tensions in the capital two months after the end of bloody street protests.

No one has claimed responsibility for either blast.

About 90 people died and some 1,900 were injured in street clashes between armed troops and demonstrators during two months of mass protests by the anti-government "Red Shirts" that ended with a bloody army crackdown in May.