BANGKOK : Thailand's appeals court Friday reduced a jail term handed out to the leader of the "Yellow Shirt" protest movement -- just a day after he was given another prison sentence in a separate case.

Media mogul Sondhi Limthongkul, who led a blockade of Bangkok's airports last year to drive allies of fugitive ex-premier Thaksin Shinawatra from government, faces a raft of libel cases by people he has criticised.

The court of appeals on Friday said it had reduced to six months a two-year jail term given to ardent royalist Sondhi by a lower court in March 2008 for defaming former deputy transport minister Phumtham Vechayachai.

"I will fight in every case but I am ready to be jailed to protect the monarchy," Sondhi told reporters after he was allowed to remain free on bail while he seeks a complete revision of the verdict with the Supreme Court.

Sondhi had accused Thaksin's ally Phumtham of being a communist, lacking faith in Thailand's status as a constitutional monarchy and of sponsoring a website that attacked the revered royal family.

"The appeals court upholds the criminal court's verdict but the two-year jail term is too harsh and severe for such an offence, therefore we reduce the sentence to six months without probation," the appeal court ruling said.

Another court sentenced Sondhi on Thursday to another two years in jail for defaming a second Thaksin ally, former central bank governor and deputy prime minister Pridiyathorn Devakula, but again granted him bail while he appeals.

Sondhi survived an assassination attempt in April that he blamed on elements in the security forces.

He founded the yellow-clad, royalist People's Alliance for Democracy (PAD), which held mass protests preceding the September 2006 coup that ousted Thaksin as prime minister.

The movement took to the streets again in 2008 and eventually forced a government led by Thaksin's brother-in-law out of government in December through the economically-devastating airport siege.

Pro-Thaksin "Red Shirt" protesters are set to hold a mass rally in Bangkok on September 19, the third anniversary of the coup. Thaksin fled the kingdom last August to avoid a two-year jail term for corruption.

- AFP /ls