By Patpicha Tanakasempipat and Panarat Thepgumpanat

BANGKOK (Reuters) - Thai opposition party leader Thanathorn Juangroongruangkit called on supporters to mobilize in Bangkok on Saturday, days after the national election body called for the dissolution of his party.

Thanathorn, 41, has emerged as the most prominent opponent of the government headed by former junta chief Prayuth Chan-ocha, 65, after his progressive Future Forward Party came a surprise third in an election in March.

The opposition Pheu Thai Party, which was ousted in 2014, won the most seats in the 500-member House of Representatives lower house. Palang Pracharat, the pro-military party formed last year by members of the junta's cabinet, came second.

Although Pheu Thai is the biggest opposition party, Future Forward has taken a higher profile in challenging the government.

In a Facebook video, Thanathorn called on people who were "fed up with a society like this" to take to the street on Saturday. It is the first time he has made such a call.

"This is the time for the people to make a noise," Thanathorn said. "If you agree with me that now is the time for people to stand up to fight, demand legitimacy, justice and equality, come out on Dec. 14."

His tweet calling for mobilization was retweeted more than 20,000 times in over two hours.

But it is not clear whether authorities will allow the gathering to take place. Police in the Bangkok district to which Thanathorn has called his followers said they had not received a request for a gathering in line with a law on public meetings.

Prime Minister Prayuth Chan-ocha told reporters it was inappropriate to organize a demonstration towards the end of the year, saying: "People should be happy around the New Year."





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Over the past two decades, Thailand has been rocked by periods of violent, months-long demonstrations broken by two coups, in 2006 and 2014.

"Thailand has been through a lot of such experiences in the past, and the damage has taught us that it does no one any good at all," government spokeswoman Narumon Pinyosinwat said.

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The army has also made plain its dislike of a new movement it accuses of plotting against the government and monarchy.

Thanathorn said this month he would not be calling for Hong Kong-style street protests.

But Thailand's election panel has asked the Constitutional Court to dissolve the Future Forward Party, accusing it of infringing laws governing political parties by accepting multi-million dollar loans from its leader, Thanathorn.

Last week, Thanathorn accused the government of unfairly targeting him and the party with legal tactics that undermined democracy in Thailand which, after the 2014 coup, was under military rule until the March election.

Last month, the Constitutional Court found Thanathorn guilty of holding shares in a media company on the date his candidacy was registered for the election, disqualifying him as a member of parliament. Thanathorn disputed the ruling.





(Reporting by Patpicha Tanakasempipat; Editing by Matthew Tostevin, Raju Gopalakrishnan and Timothy Heritage)