ISLAMABAD, Pakistan, Jun 19, 2002 (UPI) -- Pakistani President Pervez Musharraf approved Wednesday a law to register all religious schools and stop them from receiving foreign aid, and from training militant fighters, the country's information minister said. All schools must register within six months, Information Minister Nisar Memon said. Schools that don't comply will be fined or closed. Many madrasas, or religious schools, operating in Pakistan receive funds from Saudi Arabia, Iraq, Libya and Iran. Thousands are estimated to operate in the country, Memon said. An estimated 20,000 children were recruited by religious schools to fight in Afghanistan in the last several years, a U.N. report on children's rights said. "The government noted that some of the religious schools have been involved in spreading sectarianism, extremism and other unwanted activities," Memon said in explaining the new order. "The registration is also meant to have complete picture of activities of the thousands of religious schools operating in the country." Religious schools must teach science, mathematics, English and Urdu, or they will not be eligible to receive funding from the government, Memon said. Religious schools that don't register may also be confronted by government officials, he said. "Madrasas in the country, whatever the number, must be registered with the madrasa education board so that all possibilities of exploiting the youth of religious schools to spread extremism or sectarianism should be eliminated," he said. Pakistan has seen an increase in sectarian violence over the last 20 years. Many of the fighters are thought to have come from religious schools. In recent years, religious schools in Pakistan are thought to have exported fighters to Afghanistan and Kashmir. Some 253,125 students go to school at 2,715 seminaries belonging to various religious organizations in Punjab, the largest province of Pakistan, The Dawn newspaper reported. To cool tensions with India, Pakistan has promised to close down 60 to 80 "allegedly militant training camps" in Pakistan-controlled Kashmir. Of those, 18 have been closed. Most of the militants in these camps belong to various religious schools.