BANGKOK (AFP) - The former leader of the toppled Thai ruling party on Tuesday launched the first official opposition group to the nation's new military regime, bidding to draw together dissidents within the country and outside its borders.

Jarupong Ruangsuwan, an ex-minister and wanted man in Thailand, said the newly-minted "Organisation of Free Thais for Human Rights and Democracy" (FT-HD) will press for the restoration of democratic rule.

Since grabbing power from the elected government in a coup on May 22, Thailand's junta has muzzled dissent across the nation and effectively stifled any attempt to coordinate widespread anti-coup actions.

It has imposed strict media controls, shuttered opposition radio stations, and summoned and detained hundreds of people, the majority linked with the deposed Puea Thai government of ex-premier Yingluck Shinawatra and her administration's "Red Shirt" supporters.

The anti-coup group, which will operate from an unnamed country, will resist any moves by the establishment-backed junta to rig the political system in its favour, Jarupong said in the group's founding statement.

Jarupong, who resigned as Puea Thai party leader last week, decried the coup as "grand larceny" and accused the junta of violating "the rule of law, abusing democratic principles" and destroying "rights, liberties, and human dignity." The organisation is backed by a coalition of former lawmakers, academics, Red Shirt figures and other opponents of the army power grab.

The junta's foreign affairs ministry batted away their announcement.

"There is only one legitimate government, that is this administration," permanent secretary Sihasak Phuangketkeow told reporters.

Thailand's army has faced a barrage of international condemnation since claiming power.

On Monday, the European Union halted all official visits to Thailand and suspended the signing of a partnership and cooperation accord with Bangkok.

'This is just the start'

Thailand has suffered a deep political rupture since Thaksin Shinawatra - Yingluck's older brother - swept onto the political centrestage in 2001 on a wave of support from the northern portion of the country.

The Shinawatras' electoral success has shaken the Bangkok-based royalist elite - and its supporters in the military - who accuse the family of abusing democracy to sponsor massive graft and cronyism.

Some observers say the political crisis is motivated by anxiety among competing elites over who will control the country after the rule of the nation's ailing but revered king ends.

Thaksin was deposed as premier in a 2006 coup and lives in self-exile to avoid jail for a corruption conviction, although his political affiliates have continued to sweep the polls.

He draws loyalty among the urban working class and across the populous but poor north and northeast, where supporters praise him for recognising their burgeoning political and economic aspirations.

His sister Yingluck was deposed by a controversial court order shortly before May's coup, which the army said was necessary to restore order following several months of sometimes-deadly street protests in Bangkok.

"The people are demanding a fightback," FT-HD spokesman Jakrapob Penkair told AFP via Skype from London, where he was speaking on Monday.

"We will provide psychological support for all anti-coup, democratic groups inside and outside Thailand. We will provide assistance and encouragement to all demonstrators against the coup... but not of the violent kind," he continued.

"This is just the start," he said, adding the billionaire former premier and Red Shirt hero Thaksin had not joined the group.

Jakrapob was a spokesman for Thaksin's government, which was toppled by another army coup in 2006, and a founding member of the Red Shirt movement.

Coup-leading Army Chief Prayut Chan-O-Cha has suspended the constitution, gathered sweeping powers and smothered dissent, warning anti-coup protesters face military courts if prosecuted.

Thai police on Monday offered a US$15 (S$19) reward to anyone providing photographic or video evidence to help convict anti-coup protesters who have gathered in small but increasingly creative flashmobs.

In the latest strike on freedom of expression, a lone man reading George Orwell's anti-authoritarian novel "Nineteen Eighty-Four" was arrested on Sunday.