The former head of MI6 has called Labour leader Jeremy Corbyn a danger to national security who is unfit to lead the country.
Sir Richard Dearlove has written in the Mail on Sunday that Mr Corbyn would pose a "present danger to our country" if he became prime minister and has access to top-secret files.
Sir Richard, who spent 38 years with Britain's intelligence service, said Mr Corbyn's past political activities would make him a security risk if he was in possession of such sensitive information.
"Today, in the home of parliamentary democracy, we are faced with the possibility that a leader of the Labour Party who once preferred East Germany's political and economic model of government could become prime minister," Sir Richard wrote.
"A nightmare, the stuff of fantasy? Unfortunately not."
He added: "Do not even think of taking the risk of handing this politician the keys to No 10."
Sir Richard highlighted Corbyn advisers Andrew Murray - a former member of Britain's Communist Party - and Seumas Milne , who "kept company with extremist political movements".
"Corbyn, Murray and Milne have at times each denigrated their own country and embraced the interests of its enemies and opponents," Sir Richard wrote.
"Their record is not in question. A few Labour politicians have courageously spoken out against them but it is worrying that more have not done so."
