bangkok blast
Foreign businessmen lay roses for victims killed in a bomb blast outside a religious shrine near the Erawan shrine - the popular tourist site where 20 people were killed on August 17 - in central Bangkok on August 21, 2015. PORNCHAI KITTIWONGSAKUL/AFP/Getty Images)

Thai police have tripled on Friday (21 August) the reward offered for any information leading to the capture of a suspect in the Erawan shrine bombing which killed 20 people and injured 120 others.

The reward now stands at 3m baht (£535,142, €74,438) after the identity of the suspect in a yellow T-shirt caught on CCTV before the bomb blast on Monday continues to remain a mystery.

Police officers have also been ordered to stop talking to the media after conflicting accounts on the progress of the investigation emerged, Police Chief Somyot Pumpunmuang said, according to Bangkok Post.

Police are now looking for a woman dressed in black who was also captured in the CCTV footage at the time of the blast. Police spokesman Prawut Thavornsiri told reporters on Thursday that police were looking for a "woman wearing a black shirt" in connection with the blast.

"I would urge her to come forward to provide information to police," he said without giving further information.

Two other men, who were earlier sought by police, had handed themselves in and were later cleared. The pair, a Thai tour guide and a Chinese tourist, were seen standing near the main suspect in CCTV footage.

"We still have no information on international terror grops and think that there is no link to international terrorism," Somyot told reporters on Friday.

"What is clear is that it was intended to discredit the government, destroy confidence and make tourists scared and not travel to Thailand," the police chief added. So far, no one has claimed responsibility for the bombing.

Multi-faith memorial service held

Earlier Friday, a multi-faith memorial service was held at the Central World shopping mall, close to the blast site for the 20 victims who were killed in the Monday blast.

Members of the public attended the memorial service led by Deputy Prime Minister General Prawit Wongsuwon.

Following the service, participants proceeded to pay their respects to the Erawan shrine across the street, AFP reported.

Catholic cleric Monsigneur Andrew Wissanu Thanya-Anan told AFP: "Even dogs have ethics when they fight. Not these people (the attackers). It has caused terrible hurt to all Thai people."