Chuan commented after Prime Minister Surayud Chulanont indicated people who had lost influence from the political change had masterminded the blasts on Sunday night.

Chuan, a former prime minister, said the "old power" still existed like an underground group. "Do not forget that Thaksin Shinawatra was in power for five years. He built an empire with a process that used both money and power as a bargaining chip,'' he said.

Asked if the old power still used their money politically, Chuan said he believed so.

"Thaksin's money keeps rising. Do not underestimate the rich. The richest man in Thailand is not normal. Thaksin had said that dying is better than losing."

Chuan said the previous regime still had significant influence. "The old power has a strong base so they can continuously burn down schools. Some officials belong to the old power so they are not trying to reveal the truth. Money can buy people. People who receive money on a regular basis would naturally have a strong bond to them,'' he said.

Even some members of the media and some Cabinet members had links with the former heavyweights. "Look at this government, how many members of the old power exist," he said.

Former prime minister Chavalit Yongchaiyudh, meanwhile, condemned those responsible for the attacks and for causing public fear.

Thai Rak Thai Party caretaker leader Chaturon Chaisang also condemned the blasts as an evil act that lacked a sense of responsibility to the public and country.

Campaign for Popular Demo-cracy secretary-general Suriyasai Katasila described the bombs as the barbaric killing of innocent people. "This operation was politically motivated for sure, because they selected the time and the places that would create a strong impact not only locally but internationally," he said.

Suriyasai criticised Police spokesman Lt-General Achirawit Supanpesat for making a personal comment about the bomb attacks by suggesting on Sunday the previous regime was to blame.

"His comment was rather misleading than presenting the truth. Police have the duty to find evidence and arrest the culprits," he said.

If key members of the previous administration were responsible, police should be able to arrest the culprits soon, Suriyasai said. "If that is the case, the government must monitor them more closely."

He predicted the "old power" might adjust its strategies by using the masses to pressure the interim government. "They will not allow themselves to be cornered easily."