Erawan Shrine Attack
People attend a ceremony at the Erawan Shrine to commemorate the victims of the Bangkok bomb attack on Aug. 24, 2015 in Bangkok, Thailand. Getty Images/Nicolas Axelrod

An arrest warrant has been issued for an unnamed suspect in a Bangkok riverside bomb blast that took place just a day after the Erawan Shrine attack killed 20 people, Thai police said Friday. Authorities, meanwhile, are still looking for suspects and the motive behind the Aug. 17 shrine blast -- Thailand’s worst-ever bomb attack.

The second arrest warrant, which was issued late Thursday, reportedly describes the suspect as an Asian male in blue shirt, aged 25 to 30, nearly 5 feet 6 inches tall, with yellow-white skin, thick eyebrows, a high-bridged nose, and thick hair.

"Today the Southern Bangkok Criminal Court approved an arrest warrant against a man of unknown nationality" over the second blast based on surveillance footage, national police spokesman Prawut Thawornsiri said, in a statement released late Thursday, according to local newspaper Bangkok Post.

The unidentified man has reportedly been charged with "illegal possession of an explosive device, illegally detonating a bomb and premeditated attempted murder," Lt. Gen. Prawut said, adding that authorities have not concluded that the two blasts are linked.

The surveillance footage shows the man in “blue shirt” placing a bag on a riverside walkway near the Sathon ferry pier, then kicking it into water on the night of the Erawan Shrine attack. The following day, an explosion took place in the canal at the same spot, causing no casualties.

In the shrine bombing, police are looking for an "unidentified foreign man" seen in security camera footage. The man is believed to have planted the bomb in a backpack at the shrine, which is one of Bangkok’s famous tourist attractions.

However, with little clue about the suspect’s whereabouts, Thai police are facing criticism as they continue to release contradictory statements, according to reports.