President Pervez Musharraf had ordered all foreigners studying at the schools, known as madrasas, to leave by December 31 as part of a drive to stamp out terrorism and religious extremism following the July 7 London bombings.

His order came after revelations that at least one of the four London bombers -- three of whom were Britons of Pakistani descent -- had spent time at a madrasa.

Officials have said that around 700 foreign students, out of a total of 1,400, have since left and madrasas have stopped enrolling more foreign students. But hundreds remain.

Interior Minister Aftab Ahmed Khan Sherpao told Reuters that foreign students might face "some administrative issues" in leaving by Saturday.

"As such, there is no deadline for them to leave, but we want them to go back to their countries as soon as possible."

Sherpao said the government was not considering forced deportation of those who failed to meet the deadline.

"What action can we take against those students? The managements of the madrasas are responsible to arrange departures of their students and we are pushing them to help us in implementing our decision."

On Thursday, Sherpao had said that the deadline would not be relaxed.

Maulana Ghulam Rasool, a senior cleric at the Ittehad-e-Tanzeemaul Madaris, (the Alliance of Organisations of Religious Schools), told Reuters that students and madrasa managements would resist any deportations.

"Not one foreign student wants to go back," he said. "They will give themselves up for arrest if the government uses force."

Authorities in the southern province of Sindh say they have cancelled the visas of 92 foreign students still at madrasas there.