CERN, the European particle-physics collaboration that operates the Large Hadron Collider, will expel hundreds of Russian-affiliated scientists from its laboratories.

The Geneva-based organization decided to cut ties with Moscow after Russia’s 2022 invasion of Ukraine, ending nearly 60 years of collaboration, and the agreements are now lapsing. Russia has never been a full member but worked closely on nuclear physics.

Scientists tied to Belarusian institutions already saw their contracts end in July, and any Russian-linked scientists will lose access, as well as residency permits, in December.

CERN will, however, maintain links with the Joint Institute for Nuclear Research, an intergovernmental center near Moscow, a decision that is controversial for some researchers.