ISLAMABAD: Pakistan’s Supreme Court began hearing petitions today against an expired amnesty that had protected President Asif Ali Zardari and key allies from graft charges, a case that could lead to legal challenges to the US-backed leader’s rule.

A ruling against Zardari - whom opinion polls show to be unpopular - risks political turmoil just as the Obama administration and other Western allies want Pakistan to redouble its fight against al-Qaida and the Taliban near the Afghan border.

The hearing in the federal capital came as a suicide bomber struck outside a court building in the main northwest city of Peshawar, killing 10 people and wounding 45 in a fiery reminder of the threat militants pose to the nuclear-armed country.

The 17-member bench in Islamabad started hearing petitions claiming that the amnesty list of more than 8,000 people was illegal.

Civil rights activists argue that it was unjust to help so many politicians escape prosecution for alleged wrongdoing.

Zardari, who has denied a slew of corruption claims against him, enjoys general immunity from prosecution as president, but the Supreme Court could choose to challenge his eligibility for the post if the amnesty is declared illegal. Legal and political analysts are divided on whether this is likely, and most expect the process to take several months to run its course. Even some of Zardari’s critics argue it would be a mistake because it risks derailing the country’s transition to democratic rule after nine years under military ruler General Pervez Musharraf.

The session came two weeks after the expiration of the amnesty, which had been granted in a U.S.-backed deal by Musharraf to allow Zardari’s late wife, former Prime Minister Benazir Bhutto, to return from exile in 2007 and run for office safe in the knowledge she would not be dogged by corruption allegations that had forced her from office twice in the 1990s. Bhutto was killed in a suicide attack before elections won by her party, and Zardari succeeded her as party leader.

He was elected president in September 2008 by federal and regional lawmakers. Speculation over Zardari’s future has escalated after he was forced to abandon an effort to get Parliament to approve the amnesty.

He is under pressure to resign or relinquish sweeping powers he inherited from Musharraf to the prime minister and assume a ceremonial role.

Pakistan’s original constitution envisaged a parliamentary style of government, in which a popularly elected PM is the chief executive and the president is a ceremonial head of state. At today’s hearing, Chief Justice Iftikhar Mohammed Chaudhry asked for a complete list of beneficiaries and summoned the chairman of the National Accountability Bureau, an anti-corruption body formed under Musharraf, to bring a record of the cases.