The government is on the defence and says it was unaware that deposed prime minister Thaksin Shinawatra would be appearing during the state-run Channel 11 kickboxing broadcast on Sunday.
The claim follows severe criticism from Thaksin's critics, who have threatened to initiate probes against the government and its Public Relations Department (PRD).
The opposition Democrat Party said it would ask the Office of the Ombudsman to investigate who gave the broadcast the go-ahead while the Green Politics group plans to take the matter to the National Anti-Corruption Commission (NACC).
Thaksin's foes said they found it hard to believe the government had no prior knowledge about Thaksin showing up for Muay Thai Warriors, a Thai kick-boxing event on Sunday that was broadcast live on Channel 11.
The deposed prime minister presided over the tournament which was organised in Macau to commemorate His Majesty the King's 85th birthday.
Thaksin delivered a speech lashing out at the 2006 coup-makers and defending himself against allegations against him after leading the audience to light candles and sing in honour of the King.
Democrat deputy spokesman Mallika Boonmeetrakul said yesterday those who authorised the broadcast should be held accountable for allowing Thaksin, a convicted fugitive on the run, to use the state-run media outlet for his benefit.
Democrat MP for Songkhla Wirat Kallayasiri said Prime Minister Yingluck Shinawatra and PM's Office Minister Sansanee Nakpong, who oversees the PRD, could not deny responsibility.
They are supposed to ask and know who will preside over a tournament marking an occasion as important as the King's birthday, he said.
Mr Wirat called Thaksin's's appearance unethical and unlawful.
Suriyasai Katasila, coordinator of Green Politics group, called on PRD chief and Channel 11 director Thirapong Sodasri to resign for failing to properly administer the station.
He said the Green Politics group would file a petition with the NACC over the broadcast within the week.
Mr Suriyasai said Thaksin's appearance did not happen by chance.
'I think that a political group and Channel 11 executives have colluded," he said. "This is definitely not a coincidence. It hurts and disgusts many Thais."
Mr Thirapong distanced himself from the matter, saying Way Beyond 55 _ a private company _ had leased the airtime.
Ms Sansanee yesterday denied that she had anything to do with the broadcast and had no prior knowledge about Thaksin's appearance.
She said she has asked Channel 11 executives to clarify the matter and hand over time-leasing contracts with the event organiser, the World Professional Muay Thai Federation (WPMF).
She noted that the federation had previously leased time from Channel 11 to broadcast the boxing tournament.
"I never interfere in the PRD's affairs. I am in charge of policy," she said.
Gen Chaisit Shinawatra, the WPMF's president _ who is also Thaksin's cousin _ said Thaksin was informed about the boxing event but he did not confirm if he would show up. However, he admitted that some preparations were in place for Thaksin if he did show.
"There is no hidden agenda. He is a former prime minister and we give him respect," he said. "I paid Channel 11 for the airtime and I had the right to use it [as I saw fit]," he said.
Thaksin's close aide Noppadon Pattama said the broadcast was being politicised by Thaksin's political opponents. The appearance only showed Thaksin's "loyalty", he said.
He called the allegations against the former premier "painful", adding that Thaksin deserves to defend himself.
Deputy Interior Minister Pracha Prasopdee said there was nothing wrong with Thaksin's appearance and he lashed out at the Democrats for demanding an apology from Ms Yingluck.
"This is getting ridiculous," he said, suggesting the appearance "wouldn't have been a hot issue" if not for the Democrat Party.