Mar.31, 2010, 5:36 a.m. ET, Source: REUTERS

Swiss authorities to reopen corruption cases against President Asif Ali Zardari, a lawyer for the government's top anti-corruption agency told the Supreme Court on Wednesday.

The move came after the Supreme Court ordered the agency, the National Accountability Bureau (NAB), to revive all corruption cases after it threw out a controversial amnesty for Zardari, many senior government officials and thousands of political activists last year.

The revival of cases looks 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 Zardari's presidential immunity.

"In light of directions of the court on the revival of the Swiss cases, the NAB has initiated the process," Abid Zuberi, an NAB lawyer told the court.

Both Zardari and his wife, the late former prime minister 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 in Swiss accounts for a decade after Pakistan dropped out of all cases it had initiated there.

However, the Pakistani Supreme Court in December threw out a 2007 amnesty deal that shielded Zardari and others from old corruption charges and it has been pressing anti-corruption officials to revive the old cases.

Zardari has had tense relations with the independent-minded Supreme Court chief, Iftikhar Chaudhry, who was sacked in 2007 by former president Pervez 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.

A senior official of police's top investigation agency, Ahmed Riaz Sheikh, who was also a close associate of Zardari, was detained on Tuesday on the orders of the court after a similar case was revived against him.

Though Zardari's aides say he is protected by presidential immunity, he is 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 spent 11 years in jail on various charges but was never convicted.