ISLAMABAD: Pakistan's government told the Supreme Court on Wednesday that it will not reopen an old corruption case against the president, defying a judicial order that has already brought down one prime minister and now threatens his replacement.

The crisis has roiled Pakistan's political system for months, distracting attention from what many in the country believe are more pressing problems, such as the country's ailing economy and fight against the Taliban.

The dispute centers on a graft case in a Swiss court against President Asif Ali Zardari dating back to the late 1990s. The Pakistani Supreme Court has demanded the government write a letter to Swiss authorities asking them to reopen the case. The government has refused, saying Zardari enjoys immunity from prosecution while in office.

Zardari is in little immediate danger of being tried — the Swiss have indicated they have no plans to continue with the case, at least not while the president is in office. But the Supreme Court appears to consider it unacceptable for the government to ignore its orders.

The court convicted then-Prime Minister Yousuf Raza Gilani of contempt in April and ousted him from office two months later for refusing to write the letter. The ruling Pakistan People's Party rallied support to elect a new premier, Raja Pervaiz Ashraf, and has continued to reject the court's decision.

Pakistan's attorney general, Irfan Qadir, appeared before the court Wednesday and told the judges that Ashraf also refused to reopen the case because of the president's immunity.

"Your order is not implementable," said Qadir.

Judge Khosa reiterated his demand that the new prime minister write the letter to the Swiss, but also seemed to soften the court's stance, adjourning the hearing until Aug. 8 to give the government more time to come up with a solution.

The judge's somewhat softer stance could be a reaction to criticism of the court for actions that could lead to the downfall of the first civilian government poised to finish its five-year term in the country's history. Past governments were toppled by direct or indirect intervention by the country's powerful army, often with help of the judiciary.

The current government's term ends in early 2013. There is little chance of a coup, but the government might have to call early elections.

It is unclear however what sort of compromise could end the crisis. Zardari has said in the past that his government will never write the letter.

A Swiss court convicted in absentia Zardari and his late wife, former Prime Minister Benazir Bhutto, for allegedly receiving kickbacks from Swiss companies when Bhutto was in power in the 1990s.

Zardari appealed, but Swiss prosecutors dropped the case after the Pakistani parliament passed an ordinance giving the president and others immunity from old corruption cases that many agreed were politically motivated.

The Supreme Court ruled that law unconstitutional in 2009 and ordered the government to write a letter to Swiss authorities requesting they reopen the case, setting the stage for the current stand-off.

Also Wednesday, militants coming from Afghanistan fired on a paramilitary checkpoint in northwest Pakistan, wounding two soldiers, officials said.

The attack occurred in Dalasa village in the Kurram tribal area, said Rasheed Khan, a local government official.

At least 20 militants were involved in the attack, Pakistani military officials said, speaking on condition of anonymity because of the sensitivity of the issue.

The militants escaped across the border after the attack, and the Pakistani army fired artillery in retaliation, said Khan.

The Afghan government said Sunday that four civilians died when hundreds of shells and rockets fired from Pakistan hit homes along frontier areas where insurgents have staged cross-border attacks.

The government did not openly blame the Pakistani military for the artillery barrage, but the Afghans have done so in the past.

Both countries criticize each other for not doing enough to stop cross-border attacks by militants.

Elsewhere in the lawless tribal region, a gunman shot to death a Pakistani Taliban commander who masterminded a suicide attack at a volleyball tournament over two years ago that killed nearly 100 people, said Taliban spokesman Ahsanullah Ahsan.

Maulana Ashraf Marwat was gunned down Tuesday in the town of Shaktoi in the South Waziristan tribal area, said Ahsan. The Pakistani Taliban were trying to track down the killer to punish him, said Ahsan.

The suicide bombing at the volleyball tournament occurred on Jan. 1, 2010 in Lakki Marwat city, not far from South Waziristan. The attack appeared to be retaliation against residents who formed militias to drive militants out of the area, and a meeting of anti-Taliban leaders being held nearby may have been the actual target. AGENCIES