CAROLINE Lucas has branded a ruling that a long-held convention preventing the tapping of MPs' telephones has no legal basis as a "body blow for parliamentary democracy".

The Brighton Pavilion MP brought a case with Baroness Jones of Moulsecoomb to the Investigatory Powers Tribunal (IPT) over fears that surveillance by security services was breaching constituents’ right to privacy.

The Green politicians have warned of the dangerous implications the ruling could have for MP support to whistleblowers.

Ms Lucas has now called for upcoming legislation on surveillance to protection for the communications of MPs, peers, MSPs, AMs and MEPS from “extra-judicial spying”.

The Wilson Doctrine implemented by Prime Minister Harold Wilson in November 1966 lay down the policy of no tapping of the phones of MPs or members of the House of Lords, outside of a major national emergency.

Today’s ruling declared the doctrine applies only to targeted, and not incidental, interception of Parliamentary communications, and has no legal effect except that security and intelligence agencies must comply with their own guidance.

The IPT heard allegations that politicians' communications are being intercepted by GCHQ as part of the Tempora programme, which monitors and collates all electronic communications data throughout the UK.

Ms Lucas said: "This judgment is a body blow for parliamentary democracy.

“My constituents have a right to know that their communications with me aren't subject to blanket surveillance - yet this ruling suggests that they have no such protection.

"Parliamentarians must be a trusted source for whistle blowers and those wishing to challenge the actions of the Government."

Baroness Jones of Moulsecoomb said: "In a democracy there is absolutely no excuse for people who contact parliamentarians to be subject to blanket surveillance by the security services."

Rosa Curling from lawyers Leigh Day said the promises made by successive prime ministers about the Wilson doctrine were “not worth the paper they were written on”.

A Government spokesman said: "The IPT has comprehensively rejected the claim brought by a number of Parliamentarians that their communications were improperly intercepted and has found that all activity has been within the law."

The Prime Minister's official spokeswoman said the doctrine remained in place and rejected suggestions it had been rendered meaningless.

She said: "It may be that the intelligence agencies are targeting communications from a specific individual who is then in touch with an MP.

"The intelligence agencies are focusing on the individual, it does not mean they are targeting the MP."