School inspectors’ conversations with pupils and teachers at Amsterdam’s only Islamic secondary school were secretly recorded during last year’s investigation into the school, the NRC said on Friday.

The paper said four sources had either seen the taps or heard the recordings and that reporters had also been able to vouch for the authenticity of one recording themselves.

The sources said the secret recordings, made in a room set aside by the school for meetings between inspectors and others, were used by the school to keep an eye on where the investigation was heading.

Inspectors changed their way of working because of suspicions that they were being recorded, the NRC said.

One person interviewed by inspectors was later described as a ‘traitor’ by school head Soner Atasoy, the paper said. He denies making the recordings but says he was given them on a memory stick.

The school, in Amsterdam’s western docks, has been at the centre of a major row about business malpractice and fundamentalist indoctrination for over a year now.

Last July school inspectors published their report which said the school’s finances were not being properly managed and that money for education was being used for other purposes.

The Haga Lyceum has also been the focus of long-running controversy about its connections with radical Islamic preachers and earlier this year, the AIVD security service told Amsterdam mayor Femke Halsema that it was being influenced by ‘undemocratic groups’, prompting her to freeze funding.

The school has taken a combative approach, trying to block publication of the last inspection report through the courts. It has always denied being influenced by radical elements, and the inspectors’ report found no evidence that it was indoctrinating pupils along Salafist lines as had been claimed.