Pojaman's case involves a 2003 purchase of prime Bangkok real estate from the Financial Institutions Development Fund, a state rescue fund under the central bank.


If convicted she could be jailed for up to 20 years.


Earlier she told her lawyer Pichit Chueban that she wanted to turn herself in and "fight the charges in court".


"I am willing to fight the case in court in accordance with the judicial system," Pichit told The Associated Press.


Thaksin himself has vowed to return to Thailand in April, and says he is prepared to defend himself in court.


Court warrant


In August, Thailand's supreme court issued warrants for both Thaksin and Pojaman on charges of conflict of interest and fraud, each of which carries a maximum penalty of 10 years in jail.


They also face arrest for allegedly concealing Thaksin's ownership of millions of dollars worth of shares in the country stock exchange.


Thaksin, who has been living mostly in London since the September 2006 coup, denies any wrongdoing while in office.


Thailand's anti-corruption laws prohibit prime ministers and their spouses from doing business with government agencies.


Election fraud


The latest moves in the corruption case came after Thailand's election commission on Monday nullified the results for three candidates from the pro-Thaksin People Power Party on charges of vote-buying in last month's general election.


Sodsri Sathayatham, the election commissioner, said the three were PPP candidates in the northeastern province of Udon Thani, a key pro-Thaksin stronghold.


No single party won an outright majority and analysts say they see little hope of a coalition being formed anytime soon.


The resulting political uncertainty has also unnerved many investors.


'Political uncertainty'


Mike Kerley, manager of Henderson Far East Income fund, told Reuters there was "still a lot of uncertainty".


"Things are a bit better, but I wouldn't say you could be euphoric about putting your hand up and investing in Thailand at this point."


The PPP had earlier announced plans to form a coalition government with the support of several smaller groups but is now facing fraud complaints against several of its candidates that could significantly alter the balance.


"If it is a PPP government, does Thaksin come back? And if he comes back, what is the reaction?" Kerley said, adding that the uncertainty could continue for another month or two.