Brexit campaign promise unravels on Day 1: Extra £350m a week for the NHS was '˜a mistake', admits Farage

The Ukip leader was not part of the Vote Leave campaign which emblazoned slogans such as “We send the EU £350 million a week, let’s fund our NHS instead” and “Let’s give our NHS the £350 million the EU takes every week” on buses and posters.

The figure has twice been described as misleading by the UK Statistics Authority watchdog because it referred only to the UK’s £19 billion gross annual contribution and did not take into account Britain’s rebate or money that comes back from the EU. When these factors are included, the net cost was around £7.1 billion a year - or £137 million a week.

Asked on ITV’s Good Morning Britain to guarantee the money would go to the NHS, Mr Farage said: “No, I can’t and I would never have made that claim - it was one of the mistakes that the Leave campaign made.”

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His admission came as the British Medical Association (BMA) urged politicians “not to play games” with the health service in the aftermath of the referendum.

In a statement, the RCM said: “The RCM is disappointed that the outcome of the referendum is a vote to leave the EU, although of course we respect the outcome of this democratic process.

“The vote is likely to result in a period of considerable uncertainty for the UK. Whilst it will be some time before the full economic, political and social implications become clear, the impact that this will have on public finances and the funding of the NHS remains of concern to the RCM.”