BANGKOK, THAILAND - Thailand's opposition questioned premier Samak Sundaravej's loyalty to the revered monarchy on Wednesday, a serious charge that lit new sparks in a no-confidence debate on his government.

Mr Samak took power after December elections that ended more than a year of rule by royalist generals who toppled former prime minister Thaksin Shinawatra in 2006.

The military had accused Mr Thaksin of widespread corruption and of disrespecting King Bhumibol Adulyadej, who is revered with an almost religious devotion.

But a junior minister in his four-month-old government was forced to resign in May, after giving a speech last year that questioned the role of monarchy in Thailand's democracy.

Any discussion of the monarchy's role in Thailand's political life can be prosecuted under a strict lese majeste law, which allows sentences of up to 15 years in prison.

'The monarchy has been insulted as never before without any attempt from government to protect the institution,' said Nipit Intarasombut, an MP from the opposition Democrat Party, referring to the speech.

Mr Samak responded by noting that his family has served in the palace for generations, and that he has several royal decorations.

'Don't question me on my royalty,' Mr Samak said.

The premier said he had told police to investigate the speech made by Jakrapob Penkair, who implied that the palace had a role in the coup against Mr Thaksin.

'Jakrapob quit because police found that the allegation was substantial,' Mr Samak said.

The censure debate, which lasted until midnight on Tuesday, is scheduled to wrap up later on Wednesday.

A no-confidence vote is scheduled for Thursday, but could be postponed if the debate runs long.

Mr Samak has vowed to step down if he loses the vote, but that appeared unlikely as his six-party coalition controls about two-thirds of the 480 seats.

Outside parliament, the prime minister still faces street protests by the so-called People's Alliance for Democracy (PAD), which has camped outside Mr Samak's offices since on Friday.

The PAD led protests against Mr Thaksin in the months before the coup, and its latest demonstrations have raised fears of a new takeover, which has sent investors fleeing the Thai stock market.

The group's rallies exert a strong influence because its leadership is seen as a reflection of the traditional power centres in the palace and the military.

Mr Thaksin had antagonised Bangkok's elite with policies such as free health care that endeared him to the populous rural heartland.

Mr Samak had campaigned openly as a proxy for Mr Thaksin, but on Tuesday he tried to distance himself from the billionaire, who is still loathed by the Bangkok elite. -- AFP