Aitzaz Ahsan, the lawyer of Pakistani Prime Minister Yousuf Raza Gilani, leaves the Supreme Court after a hearing in Islamabad on Friday. (AAMIR QURESHI/AFP/GETTY IMAGES)

— Pakistan’s Supreme Court on Friday rejected a last-ditch appeal by Prime Minister Yousuf Raza Gilani against an imminent contempt charge, prompting fears of further political instability in the strategically vital country.

For two years, Gilani has asserted that the president enjoys absolute constitutional immunity, but an eight-judge panel of the high court, expressing exasperation, said the prime minister must appear Monday to be indicted for contempt over his refusal to obey an earlier court order to reopen old corruption cases against President Asif Ali Zardari.

The contempt charge carries penalties of six months in jail and possible disqualification from office.

The judges upheld the order demanding that Gilani’s government write to Swiss authorities to ask them to revive money-laundering charges involving Zardari that date to the 1990s.

“The order is found to be strictly in accordance with the law and principles of criminal administration of justice and therefore no interference is called for,” the high court’s ruling said.

Zardari has described the money-laundering allegations, which he denies, as part of a politically motivated witch hunt. The Swiss dropped the case in 2008 at Pakistan’s request, but a year later the Supreme Court swept away a national amnesty that had shielded Zardari and thousands of others from corruption charges.

Gilani has been in office since 2008, making him the longest-serving prime minister in Pakistan’s history. He has said he is prepared to go to jail if the court so orders.

The showdown between the high court and Gilani has raised concerns that the already weak government could fall, ushering in another period of military rule.

After the appeal was denied, Gilani’s attorney, Aitzaz Ahsan, told reporters that the prime minister would appear for the Monday hearing.

Some members of Gilani’s ruling Pakistan People’s Party have called on him to write the letter to the Swiss and end the crisis. But analysts here remain divided on whether Gilani will take that route.

They note that Gilani has served time before: He was jailed for more than five years during the 2000s after being prosecuted by Gen. Pervez Musharraf’s government for alleged abuses of power while he was speaker of the National Assembly. That case also drew claims of political retribution. A court freed Gilani in 2006 before his 10-year sentence was up.