BANGKOK (REUTERS) - Thai police said on Wednesday that two other men seen in CCTV footage near the scene of a bomb blast that killed 20 people in Bangkok are also suspects, bringing the number of suspects police have said they are actively looking for to three.

"The person in red and the person in white are also suspects," police spokesman Prawut Thawornsiri said in a televised interview, referring to two men seen in grainy closed-circuit television footage along with a man in a yellow t-shirt who police believe is linked to the attack.

A sketch of the man in yellow was released by police on Wednesday.