The leader of Thailand's onetime opposition, who led mass anti-government demonstration in the run-up to last month's military coup, has acknowledged for the first time that he acted as an adviser to the army general who seized power.

Suthep Thaugsuban, whose "yellow shirt" movement sought to topple Prime Minister Yingluck Shinawatra before her government was ousted in last month's coup, told a group of supporters in Bangkok on Monday that he'd been offering advice to army Chief Prayuth Chan-ocha for four years on how to root out the influence of Thailand's "red shirt" movement, The Bangkok Post reports.

In his remarks, Suthep made it clear that as leader of the anti-government People's Democratic Reform Committee, he closely cooperated with the coup leaders well before they launched their May 22 putsch.

"Before martial law was declared, Gen Prayuth told me 'Khun Suthep and your masses of PDRC supporters are too exhausted. It's now the duty of the army to take over the task,' " Suthep was quoted by the Post as saying.

Suthep, who as deputy prime minister in 2010 ordered a bloody crackdown on the red shirts in the capital, has pleaded not guilty to murder charges related to the incident, which resulted in the deaths of about 90 protesters.

Yingluck's brother, former Prime Minister Thaksin Shinawatra, was swept to power in a landslide promising populist measures that garnered the votes of many of the country's poor, rural rice farmers — a result that angered many among Thailand's establishment elites.

Thaksin was ousted in a coup in 2006. Yingluck was elected four years later and again earlier this year in an election boycotted by the opposition. She was forced to step down after losing a court case just days before last month's coup.

As we reported in December, months before the coup Suthep acknowledged at a rally of his supporters that he'd met with Prayuth, sparking concern at the time that a coup might be in the works. Days later, Prayuth himself helped fuel speculation.

Update at 5:40 p.m. ET. Prayuth Denies Communication With Suthep:

"Gen Prayuth insisted he had never talked or exchanged messages in private with Mr. Suthep," junta spokesman Col. Winthai was quoted by the Post as saying.

The spokesman said that as chief of a security force it would have been illegal for Prayuth to have communicated with Suthep on such matters.

The Post, quoting unnamed sources, said the junta leader was "very upset" over the opposition leader's remarks.

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