John Major has criticised the Leave campaign for portraying a "fantasy" image of Britain and warned of the risks of a "gravely weakened" EU.

Writing in the Sunday Telegraph, the former prime minister described the Brexit campaign as "sheer folly" and "verging on the reckless".

Sir John claimed that attempts to tear up Britain's existing bespoke deal were "perverse" and said the UK's influence on Europe and its relevance on the world stage could only be maintained by staying within the EU.

He also attacked some within the Leave camp for ignoring and obscuring facts that didn't suit their objectives, including statements from European leaders that there will be no trade deals without free movement and an invoice for access to the single market.

His intervention comes after Iain Duncan Smith, one of the leading figures in Vote Leave, accused the Government of issuing a "dodgy dossier" to support its campaign to remain in the EU.

Brexit campaigners have claimed that the remaining 27 EU members would be eager to arrange new trade deals with the UK in negotiations where Britain could have the advantage.

Sir John highlighted how a number of individuals, bodies and organisations, including the G20, military leaders, the governor of the Bank of England Mark Carney, and figures from the sciences, have in recent weeks spoken of the benefits of remaining in the EU.

The Leave campaign has regularly accused the Government of deploying "Project Fear" to dissuade voters from opting out of the EU - a slogan dismissed by Sir John as "flippant".

He said: "Are they (the government) really all guilty of 'interfering', 'scaremongering', or being part of one enormous plot being orchestrated by No 10? Such a notion is absurd.".