The US-based human rights group called for the Thai government to withdraw the sedition charges, as well as a series of criminal and civil defamation suits filed against political opponents by Thaksin and others in his government over the past several months.

Such charges "threaten political pluralism in the run-up to national elections expected later this year."

"Thaksin is trying to muzzle critics by filing sedition charges and an avalanche of defamation suits," said Brad Adams, Human Rights Watch's Asia director.

"The use of such draconian laws against political opponents is an extremely unhealthy signal in the run-up to elections. The government should drop these charges and engage in an open debate with its opponents."

According to the group, on April 12 the Bangkok police summoned five leaders of the People's Alliance for Democracy (PAD), which has been holding demonstrations against Thaksin, to appear at police headquarters to be served with charges of sedition.

Police allege that the five, Sondhi Limthongkul, Pipob Thongchai, Somsak Kosaisuk, Somkiat Pongpaiboon and Chamlong Srimuang, made statements that aimed to overthrowed the government and instigate public unrest.

On June 29 sedition charges were laid against nine other PAD members.

"The misuse of the legal system to silence critics, the media, and opposition parties is perhaps the most serious threat to Thai democracy," Adams said.

"Thaksin should spend more time in open public debate and less time using the police and lawyers to harass his critics."

Agence France Presse