France's highest authority on constitutional matters has approved a controversial bill that gives the state sweeping new powers to spy on citizens.

The constitutional council made only minor tweaks to the legislation that human rights and privacy campaigners as well as the United Nations have described as paving the way for "very intrusive" surveillance and state-approved eavesdropping and computer-hacking.

In a report published on Friday, the 18-strong United Nations Committee for Human Rights warned the surveillance powers granted to French intelligence agencies were "excessively broad".

It said the the bill "grants overly broad powers for very intrusive surveillance on the basis of vast and badly defined objectives" and called on France to "guarantee that any interference in private life must conform to principles of legality, proportionality and necessity".

Other critics have labelled it the French "Big Brother" act, likening it to the tyrannical and sinister government surveillance in George Orwell's novel 1984, calling it as a "historic decline in fundamental rights" and an attack on democracy.