Ms Rayner, who holds multiple positions in the Opposition including Deputy Leader and Shadow First Secretary of State, claimed the Prime Minister had violated financing rules after he took a Government plane to Teesside. The Deputy Leader claimed there are no costs on record of the Prime Minister's travel to Hartlepool using the Government plane. In a series of furious tweets, she said: "The Prime Minister has broken election finance rules and it appears that he may have broken the law too.

       "We need an investigation to get to the bottom of this - and any evidence of wrongdoing must be handed to the police."

       Previously, Ms Rayner had labelled the plane as "Sleazyjet" and accused the Prime Minister of using taxpayer money to fund campaign visits.

       Under rules set out by the Electoral Commission, all spending on by-elections must be declared.

       During the Hartlepool by-election campaign in May, Mr Johnson was seen pictured with now Tory MP, Jill Mortimer.

       Ms Rayner said in a letter to the Electoral Commission, as reported by The i: "This appears to be a clear breach of the Ministerial Code which states that Government resources should not be used for party political purposes.”

       Discussing the trip, No10 countered and stated the Prime Minister had been on official business.

       A statement revealed Mr Johnson had visited a B&Q store in Middlesbrough to promote the Government's increase in the minimum wage.

       After conducting the official business, No10 claimed the Prime Minister had made a short political visit to the by-election candidate.

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       A No10 spokesman previously said: "The Prime Minister visited Teesside on official Government business, meeting workers to coincide with an increase in the national minimum wage.

       "This was followed by a short political visit, as permitted by the Ministerial Code.”

       Ms Rayner has also written to Simon Case, Cabinet Secretary and Lord Christopher Geidt, Independent Adviser on Ministers' Interests.

       This month, the Prime Minister's spokesman added: "All relevant costs have been correctly accounted for and appropriately proportioned.

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       "At all times Government rules and electoral requirements were followed.”

       Away from the accusations levelled at the Prime Minister, Mr Johnson also held a meeting of the G7 on Tuesday.

       The group met to discuss the situation in Afghanistan with the Prime Minister hoping to press Joe Biden into delaying the withdrawal.

       Following the meeting, Mr Johnson did hint billions of pounds in Afghan assets could be unfrozen if the Taliban allows migrants free passage to leave the country.

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       He said on Tuesday: "If those huge funds are going to be unfrozen eventually for use by the government and people of Afghanistan then what we’re saying is Afghanistan can’t lurch back into becoming a breeding ground of terror, Afghanistan can’t become a narco state, girls have got to be educated up to the age of 18.

       “Those are important things that we value.

       "Those are things we fought for for years in Afghanistan, for which people in this country gave their lives.