The socialist film director slammed Robinson for favouring the Conservatives while hosting BBC Radio 4’s Today programme.
Mr Loach, who was speaking to trade unionists at a Communication Workers Union event, said he regularly “punished himself” listening to the broadcaster in the mornings.
The 80-year-old said: “You have to take an extra blood pressure tablet when you listen to it.
“They have a presenter called Nick Robinson. Nick Robinson, he showed his impartiality yesterday.”
The BBC's Nick Robinson was accused of biased reporting of the General Election
That’s Nick Robinson, ex-member of the Conservative party. That’s the partiality of the BBC
Shouting over loud jeers from his left-wing audience, Mr Loach added: “Did anybody read this? His Twitter? He said – this is Nick Robinson, impartial BBC – this is what he says: ‘No-one should be surprised that Jeremy Corbyn is running against the Establishment and is long on passion and short on details. Story of his life.’
“That’s Nick Robinson, ex-member of the Conservative party. That’s the partiality of the BBC. That’s the bias we have to complain about. That’s what we have to fight.”
Speaking to Express.co.uk, Robinson responded to the criticism, calling for the filmmaker to judge him on his work he produces.
He said: “I judge Ken Loach by the quality of the work he produces. He is a great filmmaker.
No-one should be surprised that @jeremycorbyn is running v the "Establishment" & is long on passion & short on details. Story of his life
— Nick Robinson (@bbcnickrobinson) April 20, 2017
“I think he should judge me in the same way – by the impartial interviews I do which are rigorous with all sides.”
Mr Loach has previously branded the BBC an “arm of the state”, claiming they are responsible peddling “propaganda”.
Speaking as a Jeremy Corbyn supporter, during his leadership campaign against Owen Smith, the director told a rally in central London to badger the BBC’s complaints line, telling the crowd to form a mass movement against the broadcaster.
Mr loach bemoaned the embattled Labour leader had long been subjected to media bias against him.
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He said: “The first option you get will be ‘do you want to make a comment’ – don’t go there.
“The second one will be ‘do you want to say something nice?’ – don’t go there.
“The third one will be ‘do you want to make a complaint? It’s worth it – it makes you feel better. Give it a whirl.”
Mr Loach added: “We have got to be prepared for every dirty trick.”