Bangkok: A bomb on a motorcycle exploded on Monday just outside a Hindu shrine in the centre of the Thai capital, killing at least 12 people, police and a rescue worker said.

There was no immediate claim of responsibility. Thai forces are fighting a low-level Muslim insurgency in the predominantly Buddhist country's south, although those rebels have rarely launched attacks outside their ethnic Malay heartland.

Monday's blast was near the Erawan shrine at a major Bangkok intersection.

‘All I can say now is there has been an explosion in central Bangkok involving a motorcycle bomb,’ deputy national police chief Aek Angsananond told Reuters. He said there had been fatalities, but could not confirm details.

A policeman at the scene and a rescue worker said 12 people had been killed. Media put the number of the wounded at 20.

A Reuters witness at the scene said she saw pieces of human flesh near the blast site, and a soldier later told onlookers to move back, saying they were checking for a second bomb.

‘We are now looking for another two to three bombs as we have found one suspicious object,’ national police chief Prawut Thawornsiri told Reuters.

‘There could be another explosion, so we have blocked off the crime scene and are asking bystanders to move back.’

While initial suspicion might fall on Muslim separatists in the south, Thailand has been riven for a decade by an intense and sometimes violent struggle for power between political factions in Bangkok.

Occasional small blasts have been blamed on one side or the other. Two pipe bombs exploded outside a luxury shopping mall in the same area in February, but caused little damage.

Police said that attack was aimed at raising tension when the city was under martial law.

The army has ruled Thailand since May 2014, when it ousted an elected government after months of at times violent anti-government protests.

The Erawan shrine, on a busy corner near top hotels, shopping centres, offices and a hospital, is a major tourist attraction, especially for visitors from East Asia. Many ordinary Thais also worship there.

The intersection was the site of months of anti-government protests in 2010 by supporters of ousted former Prime Minister Thaksin Shinawatra. Dozens were killed in a military crackdown and a shopping centre was set ablaze.