BORIS Johnson has told MPs that the controversial £350 million promised to the NHS splashed on the side of a bus during the Brexit campaign was an "underestimation".

One of the most enduring images of the Brexit campaign was the slogan: "We send the EU £350 million a week – let's fund our NHS instead" emblazoned on the side of the Vote Leave campaign’s bus.

Even after the referendum was over, some Brexiteers, including then-foreign secretary Johnson continued to claim the figure was correct, writing in late 2017 that "once we have settled our accounts, we will take back control of roughly £350m per week".

But the Prime Minister told the Liason Committee in Westminster that the figure was wrong as he was urged to "correct the record" by Labour's Chris Bryant.

Bryant said: "When a minister lies, they should correct the record - I assume you agree? They might do so inadvertently.

"That is the general assumption of how we do our business in parliament, that no minister deliberately lies. Though there have been occasions in our history where that has happened and a minister has been forced to resign."

"It seems that you very rarely correct the record? Why is that?"

Johnson responded: "I think I am going to need you to give me chapter and verse there as they say."

But Bryant hit back, saying: "I think there are plenty of instances where you have been told by various independent and outside bodies that the precise words that you have used have not been the precise and accurate version of events."

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The Prime Minister said: "It is commonly asserted for instance, that when we put the figure of £350 million a week on the side of a bus which went round this country causing a great deal of hoo-ha.

"That that was erroneous... That's probably one of the things you are thinking of Mr Bryant?"

Bryant said: "No, no, I'm thinking of did you sack Matt Hancock? Did you sack Matt Hancock!"

The Prime Minister said: "This was a figure that related to the gross sum that the UK gave to the EU budget.... actually it turned out to be anything a slight under-estimate!"