Mr Thaksin was given his passport back in October because he was “no longer a threat to the country”, a foreign ministry spokesman told the BBC.
Mr Thaksin lives in self-imposed exile to avoid a jail term imposed on him for abusing his powers while in office.
His passport was revoked under the previous government but the current PM is his sister Yingluck Shinawatra.
Since her administration came to power in August it has made no secret of the fact that it wished to reverse the decision, the BBC’s Rachel Harvey in Bangkok reports.
Mr Thaksin’s political adversaries are bitterly opposed to attempts to rehabilitate him, our correspondent says.
News of the new passport emerged on Friday because the government was directly challenged by an opposition Democrat MP in parliament. Earlier this month the government indicated it planned to return Mr Thaksin’s passport as “a New Year gift”.
The Foreign Ministry spokesman told the BBC the new passport was issued in Abu Dhabi in October but did not confirm whether it had been used yet.
The previous government accused Mr Thaksin of encouraging protests by his supporters and stripped him of his passport in 2009.
He was overthrown in a coup in 2006 while he was out of the country.
Mr Thaksin was later prosecuted for abuse of power and sentenced to jail, but he fled the country before the end of the trial.
He lives in exile in Dubai and has travel documents issued by Montenegro and Nicaragua.
Report by : BBC