Pakistan's Supreme Court on Friday struck down a recently passed law to protect the prime minister from being charged with contempt of court and ousted from office, like his predecessor, for refusing to reopen an old corruption case against the president.

The ruling comes less than a week before the deadline set by the court for the current premier, Raja Pervaiz Ashraf, to tell the judges whether he will obey their order to write a letter to Swiss authorities asking them to reopen the graft case.

The government and court have been locked in conflict over the issue since the beginning of the year, stoking political instability that has distracted from what many in the country see as more pressing problems, such as the struggling economy and a Taliban insurgency.

The court could repeatedly disqualify prime ministers over the issue, undermining the government and forcing an early national.