Bangkok: Political tensions flared in Thailand on Friday after lawmakers approved a controversial amnesty that could allow fugitive former premier Thaksin Shinawatra to return, triggering fresh street protests in the capital.

Opponents say the legislation, which was passed by the lower house but still needs the approval of the Senate, would “whitewash” past abuses, including the killing of unarmed protesters.

Observers warned the bill could trigger another round of civil unrest in a country with a history of political violence.

Thaksin “may underestimate just how much the issue of him and his return angers people - he excites very strong emotions personally,” said Chris Baker, co-author of a biography on the billionaire telecoms tycoon turned premier.

“It’s clearly much more serious than before but I still think there is a chance they [the ruling party] will blink - they will think it’s just too dangerous,” Baker added.

Seven years after he was toppled by royalist generals in a bloodless coup, Thaksin remains a hugely divisive figure in Thailand.

His political allies made a stunning political comeback in elections two years ago that swept his younger sister Yingluck Shinawatra into office.

MPs in the ruling Puea Thai Party-dominated House of Representatives voted 310-0 in the early hours of the morning to pass the amnesty bill, with four abstentions.

The opposition Democrat Party - which is against the amnesty - refused to take part in the vote, which came after about 19 hours of heated debate.

“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 party spokesman Chavanond Intarakomalyasut.

The bill is expected to be submitted to the non-partisan Senate on November 11, Senate president Nikom Wairatpanij said.

Several thousand people joined a rally against the planned amnesty in Bangkok for a second day on Friday, with attendance expected to swell in the evening and over the weekend.

But some observers doubt that the Democrats can mobilise the same number of supporters as during previous bouts of political unrest.

“The demonstrations on their own won’t lead to a political crisis,” said Michael Montesano, a research fellow at the Institute of Southeast Asian Studies in Singapore.

“It would require behind the scene manoeuvres on the part of the military or people close to the palace or both.”

Fresh start or whitewash?

Supporters of the legislation say it will draw a line under years of turmoil, culminating in mass pro-Thaksin “Red Shirt” protests in 2010 that left more than 90 people dead in a military crackdown.

But human rights groups have said a blanket amnesty would allow officials and protest leaders to go unpunished for alleged abuses.

“By passing a whitewash blanket amnesty bill, Puea Thai Party turns Thailand into a pariah state that doesn’t respect justice and human rights,” Human Rights Watch researcher Sunai Phasuk warned.

Thaksin, the former owner of Manchester City football club, lives in Dubai to avoid prison for a corruption conviction imposed in his absence in 2008.

He contends that the jail term - linked to a controversial purchase of state-owned land by his wife - was politically motivated.

In 2010, a court also seized $1.4 billion (Dh5.1 billion) of the Thaksin family assets for abuse of power after he was targeted by an anti-corruption panel appointed by the post-coup junta to investigate him.

As well as pardoning people involved in political protests since 2004, the amnesty would also cover those accused of crimes by organisations set up after the 2006 coup, according to a copy of the bill.

Observers say Thaksin also risks alienating his traditional supporters, including the Red Shirts, many of whom oppose an amnesty.

“The Red Shirts want justice for those who lost their lives. We don’t have a problem with Thaksin coming back but we cannot accept if it’s at the expense of justice,” said the movement’s chairwoman Thida Thavornseth.