Laws rushed through in the wake of the Leveson Inquiry pose the biggest threat to press freedom in modern times, a major report says.

Campaigners warn state regulation endangers free speech, puts local papers at risk and encourages dictators.

The report, which is backed by the Free Speech Network and key figures behind the Libel Reform Campaign, calls for the legislation to be scrapped.

Chilling: Campaigners have warned that restrictive laws proposed by Lord Justice Leveson, pictured, could have dire effects on free speech

The authors claim regulation would breach the right to freedom of expression and could deny justice in libel cases.

The study is the first comprehensive examination of the royal charter railroaded through Parliament in the wake of the 2012 Leveson report into press standards and ethics. The legislation was devised over pizza at 2am with the celebrity-backed anti-press group Hacked Off.

Entitled Leveson’s Illiberal Legacy, the report makes a devastating attack on the inquiry, saying it ‘quickly became a tool for a determined group of lobbyists to use regulation to erode press freedom’.

Opponent: Journalism professor Tim Luckhurst, pictured, said 'action must be taken now' to protect newspapers

It states: ‘Many of the recommendations which emerged demonstrated a disregard for the importance of a free press and free speech, both of which are critical to uphold in a democratic society.’

Newspapers not signing up to a state-backed press regulator could face exemplary damages in court.

The rules, which could come into force as early as next month, will also make these papers liable to pick up the costs in libel cases even if they win. No newspaper – national or local – has agreed to the state-backed system – which would end more than 300 years of press freedom.

The report warns that the exposure of the MPs’ expenses scandal would have been impossible under the new regime.

The Daily Telegraph, which broke the story, would have had to contend with the possibility of all 650 MPs taking legal action even where they had no case to argue.

The ‘chilling effect’ of this threat would have proved an ‘enormous and a significant deterrent’ to publication, the authors say. There is also an ‘imminent danger’ to local newspapers, which can ill afford the system of mandatory arbitration.

The authors call for the repeal of the sections of the Crime and Courts Act 2013 that underpin the press regulation regime and the accompanying royal charter.

They also say that when the Tories bring forward a bill of rights later this year to replace the Human Rights Act it must guarantee free speech.

The report warns: ‘Action must be taken now to protect the freedom of the press. In November, the chilling legislation will start to bite and publishers will be less free to speak truth to power.’

In the foreword, Tim Luckhurst, a professor at the University of Kent, launched an attack on press regulation campaigners such as Hacked Off.

He said: ‘Please set aside any lingering delusion that the post-Leveson debate is a confrontation between sincere reformers and rich, selfish vested interests. That misrepresentation was always cynical.

‘Today it serves only those who would exploit the victims of phone-hacking to promote a narrow ideology.’

The report highlights the global impact of a ‘noted democracy abandoning 300 years of self-regulation for the printed press with little parliamentary debate’.

Ecuadorian president Rafael Correa, who is facing criticism for police raids on opposition newspapers, has defended his actions with reference to the Leveson Inquiry.

New press laws have also been passed in Sri Lanka.

The report was produced by press freedom group 89Up with financial support from Telegraph Media Group, News UK and DMG Media, publishers of the Daily Mail.

National newspapers, including the Mail, are now regulated by the Independent Press Standards Organisation.