A leading UK civil liberties group is requesting a formal investigation into whether British intelligence services unlawfully accessed their electronic communications.

Liberty lodged a claim Tuesday with the Investigatory Powers Tribunal seeking a ruling on whether British eavesdropping agency GCHQ illegally accessed personal material.

If Liberty's claims of "out-of-control-snooping" are correct, the British intelligence services may have violated the European Human Rights Act which guarantees the right to a private personal and family life.

Liberty legal director James Welch said those in power "cannot swap targeted investigations for endless monitoring of the entire globe."

Documents disclosed by former National Security Agency contractor Edward Snowden suggest GCHQ secretly accessed fiber-optic cables carrying huge amounts of data.