The European Union risks implementing a "disastrous" budget for science, according to researchers.
Sixteen thousand academics have written an open letter calling on the EU to draw back from current financial proposals, which they claim could lead to a damaging brain drain.
Above all, they want the European Research Council (ERC) to be protected.
The ERC is the Union's premier funding agency, supporting "blue skies" investigations.
"Beyond any doubt the ERC has set the standards in the European Union, regarding quality and novelty in science and inventions - and it finds recognition all over the world," said 2016 Chemistry Nobel Laureate Prof Ben Feringa.
"In my opinion this is indeed one of the most successful accomplishments of the European Union," the Dutchman told reporters during a virtual press conference organised by the Euroscience Open Forum (Esof), adding: "I am convinced that compromising ERC budgets will be disastrous for the future of Europe."
The EU is in the process of agreeing its next seven-year multiannual financial framework (MFF), which would come into play in January.
An initial proposal from the European Commission (the EU's executive arm) of €94bn is being resisted by the European Council (the heads of member state governments) who want a lower figure of €86bn.
If the drop is confirmed it would essentially mean a flat budget for research, with the ERC's position within this framework similarly constrained.
The bloc hitherto has always increased its research spend from one MFF to the next.
The petition, produced by the Friends of the ERC, is signed by more than 16,000 scholars worldwide, including 14 Nobel Laureates, many laureates of other prestigious scientific awards, as well as over 50 leading universities in Europe.
Addressees on the letter include the three EU presidents - Ursula von der Leyen (Commission), Charles Michel (Council) and David Sassoli (Parliament) - in addition to the science ministers in the individual member states.
"If we fail to strengthen the next European framework programme, Europe's share of the global production of knowledge will diminish - there's no doubt about that," said Prof Dag Rune Olsen, rector at the University of Bergen, Norway. "This will have serious long-term consequences for European innovation and industrial leadership."
The budget now being thrashed out by the Commission, the Council and European Parliament does not include a UK contribution. Britain left the EU at the beginning of this year.
But, as part of the London-Brussels trade negotiations, the United Kingdom is seeking some sort of association to the next MFF research programme, called Horizon Europe. This would involve Britain signing up to a multi-billion-euro subscription.
UK researchers have been major beneficiaries of the EU grant process in the past, especially the funds attached to the ERC. Something approaching a fifth of all European Research Council monies have gone to UK-based grantees during its 14-year history.