Pakistan's top court on Wednesday summoned the new prime minister to appear later this month to face possible contempt charges, the clearest sign yet it could dismiss a second premier in a showdown over corruption cases.
The Supreme Court -- which disqualified and convicted prime minister Yousuf Raza Gilani over the issue -- summoned his successor Raja Pervez Ashraf to appear on August 27 for ignoring a request to ask Swiss authorities to reopen cases against the president.
It is the latest episode in a two-and-a-half-year saga in which the government has resisted demands to have Asif Ali Zardari investigated, arguing that as head of state he enjoys immunity.
The government is due to become the first in Pakistan's history to complete an elected, full five-year mandate in February 2013, but the showdown could force polls before then.
The court had given Ashraf until August 8 to write to Switzerland and last week struck down a new law passed by parliament that sought to exempt members of the government from contempt trials, clearing the way for legal proceedings against the premier.
Judge Asif Saeed Khosa said "ostensible calculated defiance" from the prime minister through "dilatory tactics and putting up excuses... may know no bounds". But he warned: "Restraint exercised by this court is also not without any limit."
He gave Ashraf notice under the contempt of court act and ordered him to explain his position in person on August 27.
Critics of the judiciary and members of Zardari's main ruling Pakistan People's Party accuse the court of overstepping its reach and waging a personal vendetta against the president.
The government had wanted the case adjourned until September. Attorney general Irfan Qadir said he needed time "to bridge the gap" between the two sides, and "find an amicable solution".
Experts say that if Ashraf does not satisfy the court, he risks being indicted for contempt, precipitating the second trial against a sitting prime minister in months.
The allegations against Zardari date back to the 1990s, when he and his wife, late premier Benazir Bhutto, were suspected of using Swiss bank accounts to launder $12 million allegedly paid in bribes by companies seeking customs inspection contracts.
The Swiss shelved the cases in 2008 when Zardari became president and the government insists the president has full immunity as head of state.
But in 2009 the Supreme Court overturned a political amnesty that had frozen investigations into the president and other politicians, ordering that the cases be reopened.
Zardari had already signed the contempt law, which sought to exempt government figures, including the president, prime minister and cabinet ministers from contempt for acts performed as part of their job.
Analyst Imtiaz Gul told AFP that Wednesday's decision showed the court was refusing to back down. "The logical consequence of the court's position is the disqualification of any prime minister who refuses to write the letter," he said.