Police in Thailand have launched a manhunt for a man caught on CCTV walking into the Bangkok shrine wearing a black backpack and exiting without it shortly before the bomb exploded on Monday evening.

Thailand’s Prime Minister Prayuth Chan-ocha said the bombing of the Erawan Hindu shrine in the capital on Monday was the “worst-ever attack” on the country.

The bomb was detonated at the popular tourist site at about 19:00 local time (12:00 GMT) on Monday, when the shrine was crowded with tourists, killing at least 20 people and injuring more than 120.

Most of the victims with Thai, but at least eight foreigners were amongst those killed in the blast.

Police are examining CCTV footage for clues about the bomb, and members of the public who were in the area around the time the bomb was detonated to share any photographs and video they have with authorities.

The motive for the attack remains unclear and no group has yet claimed responsibility.

Thailand has been marred with political unrest in recent years and Muslim insurgents continue to battle for independence in the south of the country, but neither has resulted in a bomb targeting Bangkok before.