The UK’s post-Brexit collaboration with European scientists hangs in the balance after it emerged that the EU offer of staying in the Horizon research programme could leave London with a £3bn deficit. “The financial negotiations are not in a good position and the offer that the [European] commission has made to the UK is not appealing,” Vivienne Stern, the director of Universities UK International, told a Lords Brexit committee on Thursday. Top researchers are concerned that Boris Johnson is now preparing to walk away from Horizon Europe, which is one of the most ambitious science funding programmes in the world and the successor to the €80bn (£72bn) Horizon 2020 fund. The issue is a stumbling block but Stern has urged both sides to “compromise on costs” and reach a deal that provides continuity for one of Britain’s most successful sectors. She told peers the EU had offered a “one way” financial formula to stay in Horizon Europe, under which the UK would contribute about £15.2bn to the programme’s seven-year budget, with top up funding if the the country won research projects worth more than that. But if the value of the awards to British science fell short of the investment, the UK would not be reimbursed. Stern said: “In order to receive an equivalent to £15bn in receipts, we need to win 16% of funding from the programme. We currently will win 12.7%, so that implies that even if we continue to participate at the current level, there would be a net contribution over the life of the programme’s seven years at about £3bn. Now, even we think that doesn’t look fair, and we’ve been saying to our European counterparts.” Scientists are desperate for a deal and have said they are already struggling to stay in research programmes with EU nations because of the uncertainty. While the UK government has said it will provide replacement funding to scientists in Britain, peers were told that money alone was no substitute for the “intangible” value of Horizon Europe. “Continuing involvement in European science programmes is absolutely vital to UK science,” Sir Richard Catlow, the vice-president of the Royal Society, told the Lords subcommittee on EU services. “It’s not just about money, it’s about networks and collaboration. We will be a poorer nation scientifically and a poor nation generally without.” Catlow said a “modest net contribution” to Horizon Europe was probably reasonable because of the wider benefit of remaining part of international teams. With time running out for Brexit negotiations, there are no guarantees there will be deals on elements of the future relationship with the EU beyond trade. “If we get to the end of December and there’s no negotiated outcome,” said Stern, the best thing would be to “try to get back to the table on research collaboration”. It was a bridge that could still be built, she said, and “with compromise on both sides on the cost question, it is a deal that could be done fairly quickly”. Earlier, the committee heard the UK was the “most prolific producer of research” in science and medicine after the US and China, but “was ranked first internationally every year since 2007” when measured by the impact on a particular field. Universities receive £6.5bn for research a year, with 11% of the funding coming from the EU. After the US, British scientists’ “most frequent partners” are Germany and France, Stern said. • This article was amended on 23 October 2020 because an earlier version said universities receive £600bn for research. This has been corrected to £6.5bn.