Monday's blast killed 20 people, mostly Asian visitors, leaving police scrambling to find the assailants and sending shockwaves through the nation's vital tourism sector.
Speaking after a memorial for the dead at the scene of the unprecedented attack on Thailand, national police chief Somyot Poompanmoung said the bomb was an attempt to stoke fear and uncertainty in the capital.
"The aim is to discredit the government and create a climate of fear to deter tourists," he told reporters.
"There's a lot of progress (in the case), but I can't disclose everything," he added.
Somyot also played down his earlier comments that the attack on a Hindu shrine in a tourist zone of the capital was carefully planned by a network of 10 people.
Instead he said the main suspect - captured on CCTV placing a backpack under a bench at the Erawan shrine minutes before the explosion - must have had "accomplices supporting the attack".
After days of confusing and sometimes contradictory statements from senior police and junta officials, Somyot also said he would restrict how often his subordinates speak to the press.
"I have instructed police not to answer questions from the media," he said.
Both the police and junta have at various times ruled out the possibility that a global terror network carried out Monday's bombing, but have later appeared to backtrack on the comments.
Thailand has endured a decade of political unrest, but many analysts say that the choice of target and ferocity of the attack makes it highly unlikely any Thai groups with a history of violence were involved.
Two suspects cleared
Thailand has asked Interpol for help in finding the main suspect, a young bespectacled man in a yellow t-shirt who authorities have speculated may have been wearing a disguise.
A police spokesman late on Thursday hinted that investigators are looking at whether a private dispute could be behind the blast, but refused to give further details.
Thai authorities issued an arrest warrant stating the prime suspect is a foreigner, after CCTV footage caught him nonchalantly walking away from the shrine moments before the blast, and have said they are not sure if he has already fled the kingdom.
Two other suspects who attracted suspicion after being seen on security camera footage near the main suspect at the shrine were ruled out as accomplices on Thursday.
Police said they were a Thai man who was visiting the shrine with his Chinese friend, and handed himself in to police once the pair were identified as potential suspects. He has since been cleared, along with the Chinese man who returned home a day after the blast.
With the bomber on the run Bangkok remains a city on edge, but there is little evidence of a major police sweep.
The multi-faith memorial near the shrine today drew together religious leaders from Thailand's Buddhist, Muslim, Christian, Hindu and Sikh communities.
They led prayers, mantras and musical ceremonies to commemorate the dead and more than 120 who were wounded in the rush hour blast.
Catholic cleric Monsigneur Andrew Wissanu Thanya-Anan urged unity in the face of the attack on the hugely popular Hindu shrine, which is also a place of worship for the kingdom's majority Buddhist population.
"Even dogs have ethics when they fight. Not these people (the attackers). It has caused terrible hurt to all Thai people, all religions," he told AFP.
Doves are due to be released at the shrine later today.
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