"Such a remark upsets members of the armed forces [who serve under HM the King]," Sonthi said.

Asked how the armed forces would react to the incident, he said: "I think you know what could happen if the armed forces are displeased."

According to the Army chief, peaceful demonstrations are acceptable in a democracy, but the highly revered King should not be mentioned in a disrespectful manner.

Sondhi, the media firebrand who has been co-leading the anti-Thaksin movement in the past few months, earlier mentioned the King in a manner that could be deemed as lese majeste while he attacked Thaksin Shinawatra, the caretaker prime minister.

Admiral Sathiraphan Keyanont, the Navy chief, said Sondhi's reference to the King was unacceptable and police are investigating the case.

Meanwhile, Sondhi yesterday postponed his return from Guilin in China, saying he could not get a seat on a Bangkok Airways flight.

Bangkok Airways yesterday reported it had received a bomb threat at Don Muang International Airport, resulting in the delay of its Guilin-bound flight in the afternoon.

Officials did not find any explosives aboard the jetliner and it was cleared to depart for the Chinese tourist city. Sondhi had planned to return to Bangkok last night on the aircraft.

Besides the bomb threat, a group of people had earlier said they would hold a rally at Don Muang to protest against Sondhi for making the "insulting" remark concerning the King.