The Thai authorities appeared to backtrack on an earlier attempt to downplay international links to Monday's bomb attack in Bangkok, even as they claimed "much progress" in their investigation.
While the police trebled the original 1 million baht (S$39,500) reward for information on the bomber, the son of exiled former premier Thaksin Shinawatra raised the bounty, offering another 2 million baht to the informant as well as 5 million baht to security officers involved in the arrest.
"To say there are Thais involved... without investigation would cause division among Thais," Mr Panthongtae Shinawatra wrote in a Facebook post announcing the reward.
Officials' remarks suggesting that Thais might have been involved in the attack cast aspersions on political groups now suppressed by the ruling junta, including Thaksin's supporters.
Police, meanwhile, have released two people who turned themselves in for questioning after being caught on CCTV footage with the prime suspect, who was seen leaving a backpack at Erawan shrine shortly before the blast.
No party has claimed responsibility for the bomb attack, which took place during rush hour at one of the busiest intersections in Bangkok. The violence was shocking, even for a nation roiled by political turbulence for much of the past decade.
The military government responded by trying to tighten security to avoid any long-term damage to the tourism sector, which accounts for 10 per cent of the gross domestic product in Asean's second-largest economy.
Yesterday, senior officials like Deputy Prime Minister Prawit Wongsuwan and Bangkok Governor Sukhumbhand Paribatra led rites for five religions at CentralWorld shopping centre, just across the intersection from the shrine.
Twenty people were killed on Monday, including 14 foreigners. Of the more than 100 people injured, 63 are still hospitalised. Among them are two Singaporeans.
A televised announcement by the junta yesterday declared "much progress has been made" in the investigation. "However," it added, "the details cannot be disclosed at this time." This was in contrast to its statement on Thursday that international terrorist networks were "unlikely" to be behind the attack.
National police chief Somyot Pumpanmuang was yesterday quoted by Reuters as saying: "We still have no information on international terror groups and think there is no link to international terrorism."
The government had faced heavy flak after publicising its preliminary conclusion early in the probe.
Cleaners started hosing down the area around the shrine on Tuesday, one day after the blast, with the shrine reopening on Wednesday. Workmen repainted it a day later.
A BBC correspondent found remnant shrapnel across the road from the blast and tried to deliver the potential evidence to the police, but was initially turned away.
In a statement on Thursday, the International Commission of Jurists urged: "The Thai authorities must also resist the pressure to display progress through hasty conclusions and commit unwaveringly to an investigation that meets international standards and respects all legal and due process guarantees.
"Only a credible and fair process will provide truth and justice to the many victims and survivors."
Analysts note that the attack was intended to inflict maximum casualties. On the same night of the attack, a bomb was discovered and defused across the road from the shrine. The next day, another was hurled off Sathorn Bridge by the Chao Phraya River. It missed the footpath below, detonating underwater without injuring anyone.
Locals have become more alert to suspicious objects and unattended baggage. Local media reported a few false alarms around the country involving objects found to be harmless. One was a sepak takraw ball spotted in a park in Bangkok.