AMSTERDAM — The Dutch interior ministry has acknowledged the country's secret service sometimes taps the communications of lawyers who represent terrorism suspects.

A law firm specializing in human rights complained to the ministry in April it suspected its lawyers were being tapped, violating lawyer-client secrecy.

The ministry responded by ordering the commission overseeing the agency to investigate. In a letter dated Dec. 15 and published on the Prakken d'Oliveira Human Rights Lawyers firm's website Thursday, Interior Minister Ronald Plasterk said the investigation found the secret service is entitled to tap confidential communication in some circumstances, and had correctly followed internal protocol in doing so.

However, the investigation criticized the secret service for in some cases writing up the content of lawyers' personal communications that "cannot be considered as relevant for any investigation."