The UK could be forced to spend an extra £500m a year to meet the health costs of tens of thousands pensioners returning from other EU countries after Brexit, a top think-tank claimed on Wednesday (31 May).

The Nuffield Trust explained that the 190,000 British pensioners living on the continent receive healthcare under the EU's reciprocal "S1" scheme.

But if the initiative is withdrawn and expats return to the UK, the annual cost to the NHS would be around £979m (€1.12bn).

Since Britain currently puts £500m a year into the S1 scheme, the extra cost would be around £500m

"The NHS and social care were already under pressure from tight funding settlements and growing staffing problems well before the EU referendum last year," said Mark Dayan, Nuffield Trust policy and public affairs analyst.

"But if we handle it badly, leaving the EU could make these problems even worse, given the potential impact on both the strength of the UK economy and the supply of overseas staff to both health and social care services.

"It is possible that extra funds could be found for the NHS from any cancellation of Britain's EU membership fees – but whether or not these benefits will outweigh the significant staffing and financial costs Brexit may impose on already stretched services remains to be seen.

"That depends largely on the NHS being recognised as a significant priority as we enter some of the most important negotiations in Britain's history".

The report also calculated that care homes and home-care agencies could end up as many as 70,000 staff short by 2025/26 because of the end of the free movement of people from the EU.

"These stark figures show Theresa May's extreme version of Brexit would be a disaster for the NHS," said Liberal Democrat leader Tim Farron.

"Crashing out of the EU without a deal would mean the loss of healthcare rights for British pensioners in Europe, putting huge pressure on our hospitals.

"We risk seeing nurses and social care workers from the EU leaving in their droves because Theresa May won't do the right thing and guarantee their right to stay.

"A brighter future is possible. We will stand up to a bad Brexit deal that would hit the NHS hard, and give people the final say with a chance to remain in the EU."