One CCTV suspect freed over Bangkok bomb: police spokesman

A Thai man wanted for questioning after he was seen on security camera footage "met police and was released", national police spokesman Prawut Thavornsiri told reporters, adding a second man from China in the same shot had already left the country -- but neither were "likely involved".

The main suspect, believed to be a foreigner in a yellow shirt seen depositing a backpack at the scene was still at large, he added.

The two men -- the Thai in a red shirt, and the Chinese in white -- were initially believed to be possible accomplices of the suspected bomber.

They were seen standing in front of the lead suspect as he took a backpack off and placed it under a bench. They then left the crowed shrine in central Bangkok.

Moments later the bomb exploded killing at least 20 people, mainly foreigners, wounding scores more and sparking a manhunt for the bomber.

"The Thai man is from Chiang Mai," Prawut said, explaining he had taken the Chinese man to the Erawan shrine on behalf of a mutual friend.

The Chinese man returned home a day after the bomb.

Thai authorities have given conflicting and contradictory snippets of information on their quest for the bomber.

But they say they are still confident a bespectacled man in the yellow shirt, described in his arrest warrant as a foreigner is the prime suspect.