Three student activists have been seized in Tehran. The three were seized shortly after they held a news conference to announce the cancellation of protests marking the anniversary of student clashes with security forces.

Members of a pro-reform student umbrella group say the three activists were taken away by men dressed in plainclothes as they left the news conference. One of the witnesses is quoted as saying, "We cannot call it arrest, it was a kidnapping."

Reuters news agency quotes witnesses as saying about 15 people armed with handguns pushed aside uniformed police and forced the three activists into waiting cars.

Shortly before they were detained, the activists announced they were canceling a campus protest and demonstrations in front of the United Nations offices in the capital because they feared a backlash from government security forces.

Students had earlier called the protests to mark the fourth anniversary of violent clashes between students and security forces that led to the death of one student.

Authorities in Iran have banned any commemoration of the 1999 student-police clashes by prohibiting any rallies, closing campus dormitories, postponing summer exams and vowing to crack down on any unrest.

During 10 nights of student-led protests in June, there were frequent clashes between students and security forces. The protesters were critical of Iran's supreme leader, Ayatollah Ali Khamenei, Iran's most powerful figure, as well as the slow pace of reforms under President Mohammad Khatami. The protests came to an end after a police crackdown in which thousands were arrested.