Hardline Islamist politicians, students and religious schools in Pakistan have reacted angrily to the latest move of a government crackdown on extremism.
Foreign madrassa students say their studies are peaceful
On Friday, President Pervez Musharraf said 1,400 foreign students at madrassas, or religious schools, must leave the country.
Pupils have insisted their studies are peaceful while a hardline Islamic leader called the move "inhuman".
An alliance of madrassas has threatened to end a dialogue with the government.
President Musharraf said he took the decision, the latest in a series of measures in his clampdown, because he did not want the madrassas "misused for extremism".
The schools have been in the spotlight after one of the London bombers was reported to have studied at one.
On Saturday, President Musharraf appeared at a public rally in the Swat valley in North-West Frontier Province (NWFP), again urging people to reject extremist forces.
On Sunday, Syed Munawar Hassan, a senior leader of the Muttahida Majlis-e-Amal, an alliance of hardline Islamist parties that holds power in NWFP, denounced the student move as "inhuman".
"Under what rules can you cancel somebody's visa if he is staying here with the correct travel documents?" Mr Hassan asked.
He said the alliance was planning to go to court to challenge the decision.
The ruling was also condemned by madrassa bodies.
Maulana Wali Khan, a spokesman for the Wafaq-ul-Madaris, which controls about 10,000 madrassas, said: "We knew that he would take this step to appease America and other Western nations."
Musharraf has launched a new crackdown on extremists
Another alliance of madrassas, the Ittehad-i-Tanzimat-i-Madaris-i-Dinya, told Pakistan's Daily Times it would pull out of its dialogue with the government if the move was not withdrawn.
Its secretary, Qari Hanif Jullandhry, said it would not accept any law imposed without consultation.
Foreign students at madrassas insist they are not an extremist threat.
One, Abdul Samad, who studies at the Jamia Banoria madrassa in Karachi, told Associated Press: "I am a British national and came here in 2004 to get knowledge about Islam.
"We are peace-loving people. Let us complete our education and spread a message of peace in the world."
The government is standing by its decision.
Interior Minister Aftab Khan Sherpao said on Saturday: "This process will start very soon."
He said countries had expressed concern that their nationals were being exposed to militancy.
Islamabad has come under pressure to act against extremists following the London bombings of 7 July and evidence that three of the suicide bombers had visited Pakistan.
Pakistani forces have detained hundreds of clerics and suspected militants since President Musharraf announced his new crackdown on 15 July.