LONDON (AP) — Top scientists from around Europe have warned that Britain leaving the European Union without an agreement on future relations would harm research across the continent.

The letter, signed by 29 Nobel laureates and six winners of the Fields Medal mathematics prize, urges Britain's prime minister and the head of the European Commission to ensure the "closest possible cooperation between the U.K. and the EU."

The letter says new barriers would "inhibit progress, to the detriment of us all."

The London-based Francis Crick Institute, the biggest biomedical research lab under one roof in Europe, also warned that a no deal-Brexit could cripple research. A survey of more than 1,000 staff members found that 97 percent believe a hard Brexit would be detrimental to British science.