The president of the Royal Society has warned the Tory leadership candidates that UK research could be damaged by a bad deal or no-deal Brexit.
Prof Sir Venki Ramakrishnan has presented them with an analysis showing that the UK collaborates with the EU much more than previously thought.
It shows that a third of UK research papers are co-authored with the EU scientists.
This compared with less than a fifth from the US.
Prof Ramakrishnan added that without a new visa arrangement it will be much more expensive for researchers from the EU to work in the UK compared with other countries.
British science is one of the biggest winners of the UK's membership of the European Union. It receives tens of millions of pounds more each year than it puts into the EU research budget. Membership also allows UK researchers easy access to collaborations with the best laboratories in Europe.
In a letter to Jeremy Hunt and Boris Johnson, Professor Ramakrishnan says that those benefits will be lost and with them risks the UK's pre-eminent position in research, in the event of a no-deal Brexit.
The Royal Society's new analysis indicates that links with the EU are of growing importance to UK science.
"The loss of support from European research grants and collaborations would have an immediate impact on innovation in the UK and stop valuable research in its tracks," Prof Ramakrishnan wrote to both leadership candidates.
He has also provided data which shows that it is substantially more expensive for researchers to get work visas in the UK than other nations. Currently, EU researchers working in UK labs have to pay nothing, but without a proper arrangement in place, those applying in future will have to pay thousands.
"How the UK approaches immigration directly impacts our attractiveness as a place to work or train as a researcher. As well as tackling the immediate costs barrier, we need a cultural shift within the immigration system that makes us more human and welcoming in the way we handle cases," he said.
Last month, the UK's leading research bodies urged the Conservative leadership candidates to make a pledge to put scientific research at the heart of their economic policy.