At least 28 anti-government protesters have been hurt in an explosion in Bangkok, bringing to an end several days of relative calm in the Thai capital.

Police say a device was thrown at demonstrators marching in the city centre. None of the injuries are believed to be life-threatening.

A search is underway for those behind the attack as tension mounts ahead of an early election on February 2. It is being boycotted by the main opposition party.

The probable target of today’s blast was protest leader Suthep Thaugsuban. He escaped unhurt.

Political unrest in Thailand flared in November amid calls for Prime Minister Yingluck Shinawatra to step down. It escalated on Monday when protesters, led by Suthep, brought parts of Bangkok to a standstill.

They dismiss Yingluck as a puppet of her self-exiled brother, ex-premier Thaksin, ousted by the army in 2006, whom they associate with widespread corruption.