The minister said it was "highly likely that the perpetrators are men in uniform."

"It's 90 per cent sure that it is politically motivated and only a handful of groups of people have the potential to mount these attacks," he told reporters.

He said it was unlikely that civilians would have the training to coordinate the eight small blasts across a wide urban area, and said that left "only either police or military.".

Meanwhile Prime Minister Surayud Chulanont told the National Legislative Assembly Thursday that forensics tests showed the New Year's Eve bombs were not of the same type as those used by the separatists.

"Forensics tests found that the bombs were similar to those used in the south, but I can reassure you that they are not exactly the same," Surayud Chulanont told the NLA.

"That is the reason why we have concluded that the bombings had nothing to do with the south, and rather that the ill-intentioned perpetrators are in Bangkok,"he said.

Surayud said Bangkok's major transport centres would remain under heightened surveillance to prevent further attacks, but warned Thais should brace themselves for new threats.

"The public should be prepared to deal with this new kind of threat to our lives in the future," he said.

The Nation