DESPITE a renewed crackdown by the security forces, Iran's students are looking for clever new ways to keep their campaign for democracy going. But it is a struggle. Nearly all foreign journalists, bar a handful of agency reporters, are being kept out, so that channel of communication is barred. Websites such as those of the BBC and Facebook are blocked. The text-message system has been stop-go. The authorities have randomly declared public holidays and told people to stay off the streets because of “unhealthy pollution levels”. Security men in plain clothes stop people, especially young ones, at crossroads, to check their bags and identities. Communication between Tehran and other big cities is similarly tricky; there have been reports of dozens of students being arrested at a university in the central city of Isfahan, a former capital of Persia.

The authorities have closed down Tehran's main university, where the Islamic Revolution began in 1979. Last month it witnessed bloody battles between police and students. Stone-faced security men now stand guard at the front gate, while other entrances have been padlocked. A small number of teachers and students favoured by the authorities are let in.

Final exams have been postponed until September, though a few were taken last month. Graffiti praising Mir Hosein Mousavi, the thwarted presidential challenger, have been scrubbed off, leaving a huge officially sanctioned mural depicting the Statue of Liberty hurling rocks at cowering women and children. Other centres of learning in Tehran, such as Amirkabir University of Technology and Sharif University, have also been locked down.

Many students say that all is lost. “At first, I was angry,” says one at Shahid Beheshti University. “Then I was disappointed. Now I just feel emptiness.” A recent graduate from the Iran University of Science and Technology says he and his classmates have lost hope. Above all, a sense of paranoia has taken hold. Large numbers of students enter university as a reward for joining the baseej, a vigilante militia that answers to the Revolutionary Guard, so the campuses are heaving with informers. Students are afraid to talk to foreigners. Some refuse even to glance at them.

The government has unnerved many young people by threatening to use deadly force on a larger scale. So far, it admits that a score of people have been killed. Human-rights campaigners say more than 2,000 people have been arrested across Iran. That includes perhaps a hundred senior people associated with Mr Mousavi or the pair of former presidents, Muhammad Khatami and Akbar Hashemi Rafsanjani, who have come out against Mahmoud Ahmadinejad and his mentor, Ayatollah Ali Khamenei, Iran's supreme leader. Tehran's police chief has admitted that more than 1,000 were arrested in Tehran alone but says that two-thirds have been freed.

Green is naughty

In any event, the campaign is moving underground. A core of protesters is bent on keeping the torch burning, reminding fellow students that the revolutionaries of 1979 endured nearly a year of repression and street skirmishes before they managed to overthrow the shah. Today's protesters write subversive slogans on bank notes and pour green paint onto the streets at night, taking care to mix yellow and blue rather than buy the ready-made green stuff, whose sales are carefully monitored.

None of these tactics has made much of a dent so far. Everyday life in Tehran seems to be back to normal. Traffic is once again bumper to bumper. Mellat Park, one of Tehran's biggest, is full of families with children playing football. Coffee shops are again frequented by young people flirting, despite the demure veils.

But beneath the surface, a game of cat and mouse is under way. The government is still on edge, wary that unrest could resume. One date coming up soon is the end of the 40-day mourning period since Neda Soltan, a symbol for the campaigners, was shot dead while arriving at a demonstration in Tehran. E-mails calling for more demonstrations are still circulating. Public protest has dwindled but may not be over. The atmosphere, among students and other Iranians, is: “let's wait and see”.