Justice Secretary Michael Gove has urged the UK government to increase the NHS's funding in the event of the UK leaving the EU. It comes as leading Brexit campaigners claim that leaving the EU would allow the UK to boost the NHS's budget by £100m ($145.15m) per week by 2020, nothing that the money could come from the UK's annual contribution to the EU budget.

Thousands of people took to social media on 4 June to add their voice to the discussion, with many supporting the idea that a Brexit would help boost investment in the NHS. However, the Remain campaign has hit back at the NHS spending claims, dismissing them as being "totally dishonest".

Greg Hands, chief secretary to the Treasury, told the BBC: "Doctors and nurses want to stay in Europe because they understand that quitting the single market would damage the NHS by the shrinking economy. It's totally dishonest to pretend there would be more to spend on the NHS when all credible economists agree we'd have billions of pounds less."

Although the NHS hasn't featured prominently among referendum campaigners, this isn't the first time the health sector has come up during the debate. In April, the Leave campaign noted that the UK has paid out £6.18bn ($8.79bn) to EU countries for medical treatment of British citizens abroad between 2007-2015, but was only able to recoup £405m. Brexit campaigners said that health tourism in the UK is declining and the money could be better spent elsewhere.

At the time, Labour MP Gisela Stuart, chair of Vote Leave, said: "Health tourism from the EU has cost us billions. This money could have been much better spent – it could have been invested to improve care for NHS patients. If we vote leave we will be able to stop handing over so much money to the EU and we would be able to spend our money on priorities here in the UK, such as abolishing prescription charges and investing in the NHS."

According to research from the non-partisan fact-checking charity Full Fact, the cost of providing EU citizens with medical treatment, including immigrants and tourists, while they are in the UK is £1.8bn a year. And the cost of treating EU citizens who deliberately come to the UK for medical treatment under the NHS – so-called health tourists – is estimated to be an additional £100m-£220m. However, the actual cost cannot be quantified at the current time.

According to the Department for Health, of that cost, £500m per year is recoverable. However, only £100m was recovered in 2013/14.

The UK's EU referendum will take place on 23 June, with the result expected to be announced on 24 June.

Michael Gove
UK Justice Secretary Michael Gove has urged the Government to pledge more money towards the NHS in the event of a Brexit. Chris Ratcliffe/Getty Images