Thailand's powerful military council on Wednesday declared that New Year's Eve bomb attacks in Bangkok were staged by politicians and renegade army officers loyal to exiled former prime minister Thaksin Shinawatra.

It vowed to severely punish those behind the bombings, which killed three people and wounded nearly 40 others while the city was in the midst of New Year's celebrations.

Meanwhile, the Thai capital was shaken by a series of bomb scares and threats, though no explosive devices were found.

Among the places affected were a school, a downtown luxury shopping centre, an air force base and the offices of the English-language newspaper the Nation.

"The evidence and intelligence information proves that the bombs were the dirty work of politicians who lost power and benefit. Some bad soldiers loyal to the bad politicians collaborated with them with the intention to topple this government," said Gen. Saprang Kanlayanamitr, a member of the Council for National Security.

The council was set up after generals removed Thaksin in a bloodless coup Sept. 19. It later appointed an interim civilian government to run the country until promised elections in October.

Despite the official claims, no evidence has surfaced linking anyone to the bombings, and there is still speculation that it could have been the work of Islamic separatists who have been carrying out a bloody insurgency in the country's southernmost provinces for the past three years.

Thaksin, in a handwritten letter faxed Tuesday from China and distributed by his lawyer in Thailand, accused the country's ruling authorities of unfairly implying he was behind the violence.

"I strongly condemn this act [of bombing] and I swear that I never ever think of hurting the people and destroying the country's credibility for my own political gain," Thaksin said in the letter, given to reporters.

He also said he suspected the Islamic separatists may have been responsible for the eight small blasts that shattered Sunday night's celebrations.

"I used to warn high-ranking officials that if we can't stop them… they will go to Bangkok," Thaksin wrote.

Saprang, however, said that "the bandits and terrorist groups in southern Thailand had no links or connections to the bombs in Bangkok."

No arrests have yet been made, but Saprang said that the days of compromise with the former power-brokers were over, and "from now on there will be no compromise."

The attacks capped a year of unrest in Thailand, including the coup and the increasingly violent Muslim insurgency in the south, which has claimed almost 2,000 lives since 2004.