Whistleblowers and investigative journalists will not have their freedom restricted, Downing Street has insisted, despite concerns over proposals to beef up the Official Secrets Act.

Campaigners have criticised a Government-commissioned report on official secrets as “an attack on democracy” after it recommended that whistleblowers should face much lengthier prison sentences for disclosing classified information.

It also suggested that government information which could harm the economy should be protected by the threat of criminal prosecution.