BANGKOK, Nov 21, 2008 (AFP) - The Thai general who led a 2006 coup against former premier Thaksin Shinawatra said Friday he expected anti-government protests planned for the weekend to pass off without violence.

Sonthi Boonyaratglin warned however that in future there would probably be more attacks like the grenade blast in Bangkok on Thursday that killed one anti-government demonstrator and wounded 29.

A group called the People's Alliance for Democracy (PAD), which has occupied government offices in the capital since August, has called for a blockade of parliament on Sunday following the attack.

With speculation about a possible coup still swirling after months of political turmoil, Sonthi said military intervention was unlikely at this stage but he could not rule it out.

"A coup is not the means and it's not possible now," Sonthi told AFP in an interview.

"As matter of fact, there are chances to mount a successful coup and at this time some factors are already there. But many factors are still not yet there, therefore to stage a coup is not easy," he said.

The PAD accuses the government of being a corrupt front for billionaire Thaksin and says it will not end its occupation of Government House until the administration steps down.

Its campaign erupted into violence on October 7 when clashes between police and protesters left two people dead and more than 500 injured.

Sonthi toppled Thaksin's government in September 2006, accusing the billionaire of widespread corruption and of disloyalty to the king, which is a serious offence in Thailand.

Thaksin's allies returned to power after elections last year.

Sonthi however criticised PAD leaders for a lack of strategy, and predicted more attacks against protesters in future.

"Bomb attacks against PAD will happen again and will continue," he said.

"If PAD core leaders are not strong enough it will be difficult to fight. They must know their enemy as well as know themselves -- they must assess themselves whether are ready to fight with Thaksin," he said.

He added that the PAD needed to "make more friends and reduce their enemies".

Support for the group has fallen in recent weeks as Thais tire of the bipartisan politics and of some of the group's heavy handed tactics, including an initial refusal to open a road for the funeral of the king's sister.

Thaksin, who is living in exile to avoid corruption charges, is set to make a telephone address to his supporters on December 13 which could further inflame the situation.

Sonthi however said he did not believe Thaksin would not return home any time soon.

"I am confident that Thaksin will not return to Thailand. He just wants to boost his supporters' spirit and sympathy by repeatedly saying he will return," he said.

Sonthi said the only chance for a return to normality in the kingdom was to find "neutral and accepted" people to heal the rifts in society -- although he did not say whom.