ISLAMABAD (Reuters) President Asif Ali Zardari faced more political turmoil on Wednesday as the National Accountability Bureau asked Switzerland to reopen old corruption cases against him, signalling that the Supreme Court could be looking to strip him of his immunity. Zardaris latest headache comes after the Supreme Court last year ordered the NAB to revive corruption cases against him, many senior government officials and thousands of political activists. In light of directions of the court on the revival of the Swiss cases, the NAB has initiated the process, said NAB lawyer Abid Zuberi. The revival of the cases is set to herald a destabilising face-off between the judiciary and the government, which some analysts and legal experts think might lead to a serious challenge to Zardaris presidential immunity. The amnesty law, known as the National Reconciliation Ordinance, was passed under former military president Pervez Musharraf and widely seen as the basis for a power-sharing deal between himself and former prime minister Benazir Bhutto. She was assassinated in December 2007 after returning from self-imposed exile. Both Zardari and Benazir Bhutto were convicted by a Geneva court in 2003 of laundering $13 million linked to kickbacks. But that verdict was overturned on appeal. Swiss judicial authorities in August 2008 said they had closed the money-laundering case against Zardari and had released $60 million, frozen for a decade in Swiss accounts, after Pakistan dropped out of all cases it had initiated there. Thats where things stood until Tuesday, when a senior official of FIA, Ahmed Riaz Sheikh, who was also a close associate of Zardari, was detained on the orders of the court after a similar case was revived against him. Though Zardaris aides say he is protected by presidential immunity, he may be vulnerable to legal challenges to his 2008 election as president on the grounds that the old corruption charges against him made him ineligible to stand for office in the first place. Zardari has had tense relations with the independent-minded Supreme Court Chief Justice, Iftikhar Chaudhry, who was sacked in 2007 by Musharraf. Zardari promised to reinstate Chaudhry after his party formed a government in 2008 but dragged his feet and only did so in March 2009 when protesting lawyers and opposition supporters were converging on the capital for a protest rally.