It has been said that the media only run two stories about Iran. One is the threat that Iran will acquire nuclear weapons. The other is about women wearing make-up under the chador. In both cases, the subtext is that Iran is unique – a dangerously unhinged anti-western Islamist theocracy where wearing lipstick and mascara is an exotic revolutionary act.

Real life in Iran is rather more mundane. But not good.

On 1 May, when Labour was having a really bad day in Britain, trade unionists in Iran were, as usual, demonstrating about workers’ rights on the traditional international workers’ day.

The Iranian government responded sending in the police, who beat up demonstrators, forced them from the street and arrested many of the leaders. This has become so regular that the International Trade Union Confederation, the world’s TUC, headed its condemnation with a world-weary ‘Iran: Usual May Day repression.’

Javanmir Moradi and Taha Azadi, members of the Free Union of Iranian Workers (FUIW), and another worker called Saeed Hazrati were arrested in Asalouyeh in the south. Other arrests took place in Ashnavieh and Sanandaj. In Tehran the May Day celebrations took place on 25 April. Security forces and the police blocked Chitgar Park and scared away participants.

Iranian activists report that for days the families of those arrested were kept in the dark as to where they were being held, but finally told that Moradi and Azadi were in the custody of the Intelligence Ministry.

Again, this secrecy is not unusual – the same happened when Tehran bus workers’ leader Mansour Osanloo was seized by plain-clothed thugs last summer. He is still in jail, although worldwide campaigns by trade unionists and Amnesty International have at least got him the medical treatment that he needs.

British unions, like those in Muslim Indonesia and Jordan, have demonstrated, petitioned and written to the Iranian authorities demanding they stop harassing trade unionists. Talk of military intervention by some in the west make it harder for activists in Iran, as they give the Iranians the pretext for crackdowns.

The workers’ movement was a powerful element in the overthrow of the Shah thirty years ago. It is now reviving, if still sporadic, small-scale and slow. It is based on ordinary workers’ concerns about wages being too low or not being paid at all, inadequate childcare provision and unemployment. It is part of a wider pattern of opposition with growing movements for regional autonomy, women’s freedom and free speech.

Trade unions are being repressed not because they are breaking any laws. Significantly, the trade unionists in jails across Iran have been sentenced by revolutionary courts, not the ordinary ones. These have different rules about proof and operate under different laws.

Unions are under attack partly because they offer people an alternative loyalty – loyalty to colleagues and communities, rather than to the religious authority of the Islamists.

But this is not just about theocracy. Unions threaten the factory owners and others who are making very good money out of the poverty of their workforce. Despite President Ahmadinejad’s modest lifestyle, some people are making a lot of money in Iran and they do not want trade unions to spoil that.

The free trade union movement in Iran is growing and faces increased repression. Trade unionists in the rest of the world will keep pressing for basic human rights like freedom of expression and freedom of association. All democrats should support this campaign.