Earlier, Thaksin's lawyer vowed to fight back against the army and its appointed government, who announced on Monday they were freezing 21 domestic bank accounts belonging to Thaksin and his wife.
"We have been pushed into the corner. We can no longer retreat, so we have to fight," Noppadon Pattama said.
"He has been unfairly treated, so he will return to Thailand sooner than his original plan," Noppadon said.
He said Thaksin would decide when to come back in "two or three days".
An asset examination committee (AEC) set up after the coup ordered banks to freeze Thaksin's accounts, and help trace $618m "missing" since his family's sale of its stake in Shin Corp, a telecoms company, to Singapore in January 2006.
Even though the seizure of assets was designed to stop Thaksin bankrolling opposition to the army, analysts believe it might backfire and cause supporters of his disbanded Thai Rak Thai (TRT) party to protest.
Sukhum Nualskul, a political commentator, told a Bangkok radio station: "Despite their explanations, the AEC cannot stop people from thinking it was a political decision.
"People will have sympathy for Thaksin, who they feel has been bullied."
Even though no charges have been filed in court, the AEC concluded: "Thaksin and his cronies had been corrupt and committed wrongdoings."
Thaksin came to power in 2001, promising to improve the lives of the rural poor with universal public health care and cheap credit schemes.
He was very popular in the countryside, but his opponents said he used his vast wealth to blind voters to "policy corruption" that unfairly benefited his family's companies.
One citizen, Sakol Pakdisamai, 41, a taxi driver and TRT supporter said: "I disagree with the order.
"There will be chaos because a lot of people who love Thaksin and disagree with the order will come out onto the streets."