A Russian union official says 15 members have been briefly detained by police as tensions rise in disputes involving Volkswagen and Peugeot factories.

Dmitry Trudovoi of the MPRA union said the 15 were detained Saturday while meeting at the union's office, were held for around two hours and questioned about union activities by police from an "anti-extremism" unit.

Police were quoted by Russia's Interfax agency as saying that 12 activists were held as part of an investigation into a theft near the union office.

The union has protested against proposed layoffs at a Volkswagen plant in the central Russian city Kaluga and is also active at a Peugeot and Citroen plant.

Trudovoi accuses the police of trying to disrupt his union's activities to prevent politically embarrassing street protests.