LONDON, May 23 (Reuters) - A British vote to leave the European Union would disrupt and could well delay the approval of new drugs, leaving UK regulators struggling to cope, the chairman of the country's medicines watchdog said on Monday.
Michael Rawlins, who chairs the Medicines and Healthcare Products Regulatory Agency, said the UK watchdog would need to hire hundreds more staff to handle drug applications.
"We'd have to enlarge ourselves hugely because we'd have to evaluate all new drugs. Not only that, I don't know how it would be paid for," he told reporters.
Currently, the European Medicines Agency (EMA) approves new drugs for all EU countries. While Britain could continue to take part in the EMA system if it remains in the European Economic Area, like Norway, many advocates of a so-called Brexit oppose that option.
"That would leave us entirely on our own," Rawlins said. "Barmy!"
The head of research at top UK drugmaker GlaxoSmithKline said the hiatus would come at an especially bad time, given a raft of promising new treatments in company pipelines, including novel cancer medicines and gene therapies.
"The last thing anyone needs in the middle of that is regulatory uncertainty," said Patrick Vallance, GSK's president of pharmaceutical R&D.
The strong endorsement of Britain remaining in the EU, one month ahead of a British referendum, reflects the concerns of many scientists and company executives working in the highly regulated drugs sector.
Vallance said an exit could effectively put British patients at the back of the queue for new medicines, noting that non-EU countries like Canada and Switzerland typically took around 150 days longer to approve new medicines than the EMA.
Industry leaders have been warning for months that a Brexit vote would force the EMA to relocate from its current base in London, and Rawlins said Sweden, Denmark and Italy were all keen to host the body instead.
The exact implications of a vote to leave are still unclear but lawyers believe it would create legal uncertainty in the pharmaceuticals industry.
Prime Minister David Cameron said on Monday that quitting the EU would be economic self-destruction for Britain, presenting a finance ministry report warning of recession, a tumble in the pound and half a million job losses.
Recent opinion polls have shown voters are leaning towards an "In" decision on June 23, but pollsters say the outcome remains too close to call.
Editing by Mark Heinrich