Dutch law firm Prakken d’Oliviera and the criminal lawyers’ association are in court on Tuesday in an effort to stop the security service AIVD tapping lawyers’ phone calls.

Prakken d’Oliviera made a formal complaint to home affairs minister Ronald Plasterk about its phones being tapped last year. Although lawyers’ phones are not supposed to be listened to, this can be done by the security service if there is ‘serious justification’.

Prakken d’Oliviera’s high-profile clients include Pim Fortuyn’s killer Volkert van der Graaf, terrorism suspects, animal rights activists and PKK leader Abdullah Öcalan, the Volkskrant says on Wednesday.

The security service regulator CTIVD has confirmed the law firm’s suspicions and says in some cases the security service has acted in an ‘unacceptable way’, the paper says.

Nevertheless, Plasterk is refusing to hand over the CTIVD report and in a briefing to Prakken d’Oliviera did not say if the phone taps had been stopped.

Lawyer Michiel Pestman said the law firm had no choice but to go to court to have the phone taps removed. ‘It is in the interests of the legal system that we can talk to our clients in confidence,’ he said. ‘Otherwise we are unable to check up on the government.’