Boris Johnson has been branded a “racist” in the House of Commons by the Westminster leader of the SNP.

Ian Blackford launched his attack on the front runner to become Prime Minister and was rebuked by The Speaker, John Bercow.

The SNP MP was advised by The Speaker, during Prime Minister’s Questions, to withdraw the allegation of racism but he refused to do so.

Without naming him, it was clear his target was Boris Johnson.

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Mr Blackford said: “Words matter.

“The man who published those words in his magazine the Prime Minister thought was fit for the office of her top diplomat.

“He said that Scots should be banned from being Prime Minister and that a pound spent in Croydon is worth more than a pound spent in Strathclyde.

“This is a man who is not fit for office.

“Not only is the member racist he is stoking division and has a record of dishonesty.”

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John Bercow intervened and said: “If referring to a current member he should be extremely careful and should have notified the member in advance I urge him to weigh his words.

“And I think it would be much better if he would withdraw any allegation of racism against any particular member. I don’t think this is the forum and I don’t think it’s the right way to behave.

Ian Blackford said he had informed the member.

He continued however with his reasons for calling Mr Johnson a racist.

He added: “The member has called Muslim women letterboxes, described African people as having watermelon smiles and another disgusting slur that I would never justify by repeating. If that’s not racist I don’t know what is.”