THE Prime Minister has been slammed for unleashing a "political attack"on Sadiq Khan during a Government press conference on coronavirus.

Mr Johnson accused Mr Khan of “blowing” Transport for London’s (TfL) finances through an “irresponsible fares policy” after he had left them in “robust good order”.

He added: “And I’m afraid there was a black hole in TfL’s finances even before Covid began as I’m sure you and your readers all recollect.”

The comments made on Monday during a televised coronavirus press conference, at Downing Street’s £2.6 million media briefing room, were said during the pre-election purdah for the London mayoral election on May 6.

Ashton and Failsworth MP and Labour’s deputy leader, Angela Rayner, has called for an investigation into the incident and accused Boris Johnson of a “political attack” on Mr Khan who is standing for a second term as mayor of London as the Labour candidate.

In a letter to the Cabinet Secretary, Ms Rayner has requested that the Prime Minister issue a public apology for misusing public resources and misleading the public.

Under the Ministerial Code, Government ministers are banned from using Government resources for party political campaigning during an election period.

The restrictions, outlined in the Local Government Act 1986, ban government officials from publishing “any material which, in whole or in part, appears to be designed to affect public support for a political party”.

In her letter, Ms Rayner states that in the four years Sadiq Khan was Mayor before Covid hit, he reduced the operating deficit of TfL, left by the previous Mayor, by 71 per cent and increased cash reserves by 13 per cent.

She adds that in the last few years London has been the only major city in western Europe that hasn’t received direct Government funding to run day-to-day transport services and as a result was hit hard by a 95 per cent fall in passenger numbers during the pandemic.

Last month the entire Cabinet was accused of breaching the Ministerial Code for failing to declare financial interests, with Labour Party analysis showing that during the Covid crisis £1.9bn in Government contracts was awarded to companies with links to the Conservative Party.