Pakistani authorities have questioned students, teachers and administrators at one of two religious schools believed to have been visited by a suspect in the London (search) bombings, intelligence and school officials said Saturday.

Police and Interior Ministry (search) officials, meanwhile, denied reports that arrests had been made in the case.

Pakistan's Foreign Ministry also announced that Prime Minister Shaukat Aziz (search) postponed this month's scheduled visit to Washington and Canada. The prime minister was to meet with President Bush during a July 28-30 visit. No reason for the postponement was given.

The intelligence officials, who spoke to The Associated Press on condition of anonymity because of the secretive nature of their jobs, said agents were dispatched to the Jamia Manzoorul Islam seminary in central Lahore, one of two religious schools — or madrassas — allegedly visited by 22-year-old Shahzad Tanweer, who is believed to be one of the four bombers who attacked London's transit system July 7.

School spokesman Asad Farooq acknowledged that intelligence agents were around on Saturday, but he denied that Tanweer had ever been at the school.

"Our hands are clean. We are not involved in any such activities. We are simply running an education facility," Farooq told the AP. "Our doors are open and anyone can visit us and see what goes on here. We have no link with Shahzad Tanweer or any other foreign students at our madrassa."

The operations chief for Lahore police, Amir Zulfikar, denied a report by an international news agency that two people were arrested in Lahore.

"We have made no arrests in Lahore either today or last night," he said.

Brig. Javed Iqbal Cheema, the head of Crisis Management at the Interior Ministry, also told AP that no arrests had been made in Pakistan in connection with the London bombings, which killed 55 people, including the bombers.

It was not clear if authorities went to the other school allegedly linked to Tanweer, the sprawling Markaz Taiba in Muridke, north of Lahore. Intelligence officials say Tanweer spent four or five days at the school during the past year, then traveled to Faisalabad to meet with Osama Nazir, a militant from the al-Qaida-linked Jaish-e-Mohammed group.

Mohammed Azam, who is in charge of the 60-acre complex, denied that Tanweer had ever been there. The complex includes a mosque, religious school, housing and farmland.

"This is a pack of lies," he said. "They want to malign Islam. They want to target the religion of Islam and Muslims."

The school is linked to Lashkar-e-Tayyaba, an outlawed Sunni Muslim group believed to have been behind a deadly 2001 attack on India's Parliament.

Tanweer's uncle, Bashir Ahmed, said in England that his nephew traveled to Lahore earlier this year to study Islam.

On Friday, intelligence officials visited two religious schools — Masjid Ibrahimi and Masjid Abu Huraira — in Faisalabad, 75 miles southwest of Lahore, and showed pictures of Tanweer to students, teachers and administrators. There was no confirmation, however, that Tanweer was at the institutions.

In November, intelligence agents arrested Nazir from Masjid Abu Huraira during a raid. On Thursday, Nazir told police from jail that he had met with Tanweer, but it was unclear where the meeting occurred or whether there was any link between that encounter and the London bombings.

On Friday, President Gen. Pervez Musharraf urged authorities to root out extremism in the country, confiscate material that preaches hate, ban gatherings of extremist groups and stop radical religious organizations from collecting money.

"We owe it to our future generations to rid the country of the malaise of extremism," Musharraf told law enforcement officials during a ceremony in Rawalpindi, near the capital, Islamabad.

He stressed that the move was not anti-Islamic but rather aimed at taking Pakistan forward "as a modern, dynamic, progressive, forward-looking Islamic state."

Three of the four suicide bomb suspects — Tanweer, 18-year-old Hasib Hussain, and 30-year-old Mohammed Saddiq Khan — were Britons of Pakistani ancestry. Reports say the fourth suspected attacker was Jamaican-born Briton Lindsey Germaine.