THE government was forced yesterday to release secret documents which show that GCHQ and MI5 actively targeted legally privileged conversations between lawyers and their clients.

Legal privilege is a central tenet of British law, protecting confidential communication between lawyer and client.

However, the documents published this week show that for years GCHQ and MI5 advised staff that they could “target the communications of lawyers” and use legally privileged material “just like any other item of intelligence.”

Legal charity Reprieve director Cori Crider said: “The documents clearly show that MI5’s and GCHQ’s policies on snooping on lawyers have major loopholes. This raises troubling implications for the whole British justice system. In how many cases has the government eavesdropped to give itself an unfair advantage in court?”

The documents also reveal that until recently the intelligence agencies had no proper information barriers to prevent intercepted lawyer-client communications from being shown to lawyers or government officials involved in cases against the intelligence agencies.

MI5 only put in place such barriers in January while MI6 has almost no guidance for its officers on the interception and use of such material, it is revealed.

The disclosure comes in response to a case brought in the secretive Investigatory Powers Tribunal (IPT) by the Al-Saadi and Belhadj families, who were subjected to rendition and torture in a joint CIA-MI6 operation in 2004.

The families — assisted by Reprieve and solicitors Leigh Day — allege that, by intercepting their privileged communications with their lawyers, the government has infringed their right to a fair trial.

The documents explicitly acknowledge that in at least one (undisclosed) instance involving the use of privileged material “the potential for ‘tainting’ was identified.”

Lawyers for the Belhadj and Al-Saadi families argue that this means there is also a real risk of “tainting” in the High Court case brought by their clients.

Partner at Leigh Day Richard Stein said the documents highlighted “how the security services instruct their staff to flout these important principles in a cavalier way. We hope the tribunal will tell the government in no uncertain terms that this conduct is completely unacceptable.”