The agency said that even though the King's principal private secretary, Arsa Sarasin, is the younger brother of businessman Pong Sarasin, he "has no connections whatsoever" with the issue.

It said Sondhi made "incorrect allegations" against the royal secretary. "Sondhi's statement indicated that he failed to double-check the facts and had intended to frame and cause damage to Arsa Sarasin and the Office of His Majesty's Principal Private Secretary," read the letter sent to Thailand Dot Com Co.

The company operates the TV programme called "Yam Fao Phaendin" (Guard of the Land), on which Sondhi made the statement in question on April 27.

The letter, dated April 30, was signed by Arsa's deputy, Jitrapat Krairiksh.

Sondhi had said an amendment to the anti-corruption law passed by the National Legislative Assembly had been "stuck" for a month after being submitted for royal endorsement, and suggested the "delay" could be due to Arsa and Pong's family ties.

Pong was a major shareholder in Kularb Kaew, a company accused of acting as a nominee to Singapore's investment arm Temasek Holdings in its controversial purchase of shares of telecom giant Shin Corp from ex-PM Thaksin Shinawatra's family.

In its letter, the agency said it had received the amendment from the Cabinet secretariat on April 2 and forwarded it to the Privy Council on April 10. It received royal endorsement on April 22, after the long Songkran holiday, and was returned to the Cabinet secretariat on April 24.