Three leading Iranian student activists were arrested minutes after holding a press conference to blast the Islamic regime for banning events marking the fourth anniversary of bloody student clashes with security forces.
The arrests were made after activists from the Office to Consolidate Unity (OCU) -- a pro-reform student umbrella group -- said President Mohammad Khatami had failed in his drive for reforms and alleged the hardline-controlled judiciary was trying to prevent freedom of thought.
"Since we believe that Khatami's reforms have come to an end, we wanted to stage a sit-in opposite the UN," the OCU's Reza Ameri-Nassab said moments before he was arrested, adding the gathering was postponed on the advice of supportive MPs.
"But it is not forgotten... our demands are for the immediate release of our eight fellow students from the OCU (arrested during unrest last month) as well as those spelled out in our open letter to Kofi Annan," he said.
On Tuesday, the OCU wrote to the UN secretary general, denouncing what it said was a "dark chapter" in Iran's history and a "political and social apartheid" that it argued deserved UN investigation.
Ameri-Nassab also said his group had no confidence in Iran's judiciary -- controlled by religious hardliners -- because the institution "is trying to eradicate all sources of independent thought."
And he said events to mark the July 9, 1999 student-police clashes in Tehran -- in which at least one student was shot dead and hundreds of others arrested or injured -- would be held at the beginning of the next academic year in September.
The activists also denied the OCU was behind last month's 10 days of unrest, which were marked by more violent clashes, the chanting of virulent anti-regime slogans and thousands of arrests.
Minutes after the press conference ended, three activists were pushed to the ground and then taken away in a car by plain-clothes men, witnesses said. The detained were named by the OCU as Ameri-Nassab, Ali Moghtaderi and Arash Hashemi.
The remaining students then locked themselves back in the central Tehran building, and called for the help of reformist MPs.
Iranian authorities had banned any events marking the 1999 unrest in a bid to prevent a fresh resumption of anti-regime protests.
Tehran University's Amir Abad campus and dormitory complex, the epicentre of the street battles of 1999 and 10 days of unrest last month, has been closed off for a week while a state-sponsored religious event is being held nearby.
Off-campus protests or gatherings have also been banned, even though Khatami last month asserted that the holding of peaceful demonstrations was a "natural" right.
Journalists also received written instructions not to cover any illegal gatherings.
Many students said they were still reeling from the tough crackdown that ended the June 10-20 protests, which saw some 4,000 people arrested and bloody clashes between demonstrators and rioters on one side and well-armed hardline Islamist vigilante groups on the other.
In a bid to ease tensions, the conservative judiciary has released a number of detained students, but at the same time made it clear that any further unrest -- branded as the work of arch-enemy the United States -- will not be tolerated.
Some of the students detained in the 1999 unrest -- in which at least one student was killed and hundreds were injured or arrested -- are still in jail.
United States-based Farsi-language opposition channels, which played a major role in encouraging people to take to the streets last month, have also had their broadcasts increasingly jammed in Tehran while police and militiamen have stepped up raids to seize illegal dishes.
In an interview with the hardline Jomhuri Eslami newspaper published Wednesday, powerful former president Akbar Hashemi Rafsanjani boasted that Britain and the United States had failed in what he said was "pre-planned strategy to topple the regime."
He said the June protests -- which drew messages of support from British Prime Minister Tony Blair and US President George W. Bush -- only required a minimal response by security forces before being put down, and were "a good test for regime's power and showed how much weight the US carries."