Thaksin's spokesman Pongthep Thepkanchana confirmed that the divorce took place in a Thai Consulate in Hong Kong last week, but said he did not know why.

While Mr Pongthep declined to confirm that it was caused by Thaksin ignoring wife Khunying Potjaman's advice to leave politics for good, one source dismissed the theory, saying that 'Thaksin and his wife remain very close, and they have grown even closer since their problems began in Thailand.'

The overarching theory is that the couple wants to protect their 76 billion baht (S$3.3 billion) worth of assets, which would be at risk should Thaksin be found guilty in a major corruption case which goes to trial in December.

That speculation has since been shot down by lawyers, said The Bangkok Post.

Mr Sak Korsaengruang, from the now dissolved Assets Scrutiny Committee which ordered the freeze on the Shinawatras' assets, said that the divorce would not free the couple's fortune.

Democrat MP and party lawyer Thaworn Senniem agreed. He said: 'The divorce cannot attribute the money to any one side - it is still jointly owned and they would both need to prove how the money was earned. I think it is purely a personal decision.'

A source cited in a Bangkok Post report supported this view. Ms Khunying is reoprtedly tired of following Thaksin overseas.

The source quoted Thaksin as telling MPs who met him in Hong Kong recently: 'Khunying Or (Ms Khunying's nickname) has had enough of politics. We have built up everything together. This loss (the divorce) is the greatest loss since the Sept 19, 2006 coup.'

Sources close to Thaksin's family said the divorce was 'on paper only', so that both could pursue separate agendas.

For Thaksin, it is to continue his fight against his political enemies, particularly the People's Alliance for Democracy (PAD).

Ms Khunying, on the other hand, would be able to apply for a visa in Britain and raise their three children there.

Mr Sak is also convinced that Ms Khunying wants to appeal to Britain against the revocation of her visa on grounds that she is no longer related to Thaksin and has nothing to do with political conflicts concerning him.

The couple's entry visas to the United Kingdom were revoked after a Thai court found him guilty of power abuse in a land purchase sale case.

In yet another theory, Thaksin's family and Ms Khunying's Damapong family are said to be at odds. Damapong is Ms Khunying's maiden name.

Said source quoted by Thai media: 'While Thaksin was prime minister, political power rested with the Damapong family led by Khunying Potjaman and her brother Banpot Damapong.

'Today with Mr Somchai as prime minister political power rests with the Shinawatra family led by Yaowapa Wangsawat. The Damapongs are excluded and are suffering the political impact.'

Mrs Yaowapa is Thaksin's younger sister and Mr Somchai's wife.

Mr Somchai has so far declined to comment on the divorce, according to a report in The Nation on Monday.

He said: 'This is a personal matter. I don't know if it would have any effect on legal cases. But please don't ask me about other people's business.'

He said both he and his wife did not talk to Thaksin about the matter.