Media playback is unsupported on your device Media caption The BBC's Jonathan Head: "It's a very, very controversial proposal"

Thailand's lower house of parliament has passed a political amnesty bill that critics say could allow the return of former PM Thaksin Shinawatra.

The amnesty applies to offences committed during the political turmoil after Mr Thaksin was ousted in a coup.

The lower house passed the controversial bill in the early hours of Friday. It now goes to the Senate.

The opposition Democrat Party has warned that the passage of the bill will trigger street protests.

It did not take part in the vote, but the bill passed by 310 votes to 0.

The bill's passage through the Senate is less certain, reports the BBC South East Asia correspondent Jonathan Head, as half its members are appointed.

But this could happen as early as next week and would almost certainly provoke further protests.

Advocates of the bill say it will draw a line under the political turmoil that resulted from the military coup in 2006 that removed Mr Thaksin from power, leaving Thailand bitterly divided.

Thailand's troubles Sept 2006: Army overthrows government of Thaksin Shinawatra, rewrites constitution

Army overthrows government of Thaksin Shinawatra, rewrites constitution Dec 2007: Pro-Thaksin People Power Party wins most votes in election

Pro-Thaksin People Power Party wins most votes in election Aug 2008: Mr Thaksin flees into exile before end of corruption trial

Mr Thaksin flees into exile before end of corruption trial Dec 2008: Mass yellow-shirt protests paralyse Bangkok; Constitutional Court bans People Power Party; Abhisit Vejjajiva comes to power

Mass yellow-shirt protests paralyse Bangkok; Constitutional Court bans People Power Party; Abhisit Vejjajiva comes to power Mar-May 2010: Thousands of pro-Thaksin red shirts occupy parts of Bangkok; eventually cleared by army; dozens killed

Thousands of pro-Thaksin red shirts occupy parts of Bangkok; eventually cleared by army; dozens killed July 2011: Yingluck Shinawatra leads Pheu Thai party to general election win

This turmoil included the occupation of Bangkok's main airport in 2008 and then two months of street protests in Bangkok in 2010 that left about 90 people - mostly civilian protesters - dead.

But critics say the amnesty would allow human rights abuses to go unpunished.

"The proposed amnesty would allow officials and protest leaders who have blood on their hands to go unpunished," said Brad Adams, Asia director of Human Rights Watch, on 21 October.

"By whitewashing past abuses, the government denies justice to victims and tells future abusers they have little to fear."

'Petitioning'

The opposition believes the bill is aimed at facilitating Mr Thaksin's return, without having to serve a jail sentence.

Thaksin Shinawatra has lived in self-imposed overseas exile since being convicted of corruption in 2008, charges he says are politically motivated.

The amnesty - initially limited to ordinary protesters charged over involvement in past street clashes - was suddenly expanded two weeks ago to include anyone investigated by agencies set up after the 2006 coup.

It was as a result of one of those investigations that Mr Thaksin was jailed, our correspondent reports.

In the wake of the coup Mr Thaksin remained popular with rural voters and both general elections since the polls have seen parties allied to him elected.

His sister Yingluck Shinawatra is currently the prime minister.

The opposition says it plans to challenge the legislation.

"We will continue our fighting in the street until the bill is aborted. There are other avenues such as by petitioning the Constitutional Court," said Democrat Party spokesman Chavanond Intarakomalyasut.

On Thursday, as the bill was being debated, thousands of people rallied against it outside a railway station.