The backbench MP, who is gaining momentum in the race to succeed Ed Miliband, refused to deny being a Marxist during a BBC television interview yesterday.

He insisted that his ambition was to be prime minister and called for public ownership of the railways, energy firms, Royal Mail and telephone networks.

His Left-wing rant provoked dismay among moderate Labour figures, who warned that the party was heading for “oblivion”.

Pressure was growing last night for the contest to be abandoned because of fears that communists and other hard-Left extremists were signing up in droves to vote.

Mr Corbyn, 66, was quizzed about his views on Marx, the author of the Communist Manifesto and Das Kapital, by BBC interviewer Andrew Marr yesterday.

The Islington North MP said: “Marx obviously analysed what was happening in a quite brilliant way and the philosophy around Marx is fascinating.

“He was essentially a fascinating figure … from whom we can learn a great deal.”