The bomb attack that killed 20 people at Bangkok’s Erawan shrine on Monday was carried out by a “network”, Thailand’s chief of police has said.
Police have released a sketch of the main suspect, a man in a yellow T-shirt who was filmed by security cameras leaving a backpack at the shrine.
Police later said two other people seen on CCTV were being treated as suspects.
Prime Minister Prayuth Chan-ocha has described the incident as the worst-ever attack on Thailand.
The Hindu shrine, popular with tourists and Buddhists, reopened yesterday.
Police chief Somyot Poompanmoung told the Associated Press news agency that the shrine attack was the work of more than one person.
“He didn’t do it alone for sure,” he said, referring to the main suspect. “It’s a network,” he added, without giving further information. But he said he was certain that Thai citizens were involved in the bombing.
Although the main suspect in the footage has not been identified, an arrest warrant for him has been issued by Bangkok’s Southern Criminal Court. It accuses an “unnamed foreigner” of conspiracy to commit “premeditated murder” and weapons offences.
Police spokesman Prawut Thawornsiri said in a TV interview that the man could be of “mixed origin”.
A reward of one million baht ($28,000; £17,950) has been offered for information leading to his arrest.
Mr Prawut also said that two other men seen in the grainy CCTV footage were being sought. “The person in red and the person in white are also suspects,” he said.
The BBC’s Steve Evans in Bangkok says the new information implies this may have been an organised international operation, perhaps with a religious motive.
The prime minister urged the main suspect to surrender to the police because he might otherwise “get killed to stop him from talking”.
Mr Prayuth told reporters the man must have been hired to plant the bomb.
However, our correspondent says there are indications the main suspect was driven to the airport after the attack and may well have flown.
An arrest warrant has been issued for an “unnamed foreigner”
The statue of the Hindu god Brahma was slightly damaged in Monday’s attack
The shrine reopened at about 08:00 local time (01:00 GMT), with a handful of people arriving to place flowers or light incense in front of the slightly damaged statue of the Hindu god Brahma.