IAN Blackford branded Boris Johnson a lying “charlatan” during a heated exchange about Tory plans for a Westminster power grab.

The SNP Westminster leader hit out during Prime Minister’s Questions, refusing to back down when cautioned by the Speaker.

The Skye and Lochaber MP took aim at the Tory leader over the UK Government's Internal Market Bill after the white paper for it was published.

Blackford said: "This legislation breaks international law, but it also breaks domestic law. The Prime Minister and his friends – a parcel o’ rogues – are creating a rogue state, one where the rule of law does not apply. Why does the PM think he and his friends are above the law?"

Johnson rejected the accusations, claiming the Internal Market Bill was about protecting the economy and should be welcomed across the UK.

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Blackford continued: “What the Prime Minister said is complete rubbish, and the Prime Minister knows it. His own white paper was clear that state aid is going to be grabbed back from Scotland and handed to Westminster.

He urged Johnson to heed warnings from the National Farmers' Union, the Constitutional Affairs Committee and the General Teaching Council for Scotland about the threat the legislation poses to devolved power.

“Scotland is speaking out, and I state that the Scottish Parliament will reject this attack on devolution. Will the PM break domestic law, disregard the settled will of the Scottish people, ignore the concerns of Scotland’s communities and press ahead with his will?"

Johnson claimed attacks on the Bill are “totally illogical” and confirmed the Government will press ahead with its plans. He said the legislation represents a significant transfer of powers and sovereignty to Holyrood.

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The SNP Westminster leader could be heard calling the PM a lying “charlatan” during his response.

That prompted Speaker Lindsay Hoyle to demand that Blackford withdraw his accusation that the Tory leader was lying.

Blackford refused, stating: “It’s on the face of the Bill that the UK Government is going to trample over devolution … that is not a lie.”

Nevertheless, the Speaker said he accepted that Blackford had withdrawn it.