The chief of the CERN physics laboratory says China’s decision to pause its major particle accelerator project presents an “opportunity” to ensure Europe’s rival plan goes ahead.

Ten years ago, China announced its intention to build the Circular Electron Positron Collider (CEPC), which at 100 kilometers (62 miles) long would be the world’s largest particle accelerator.

But Beijing recently put the project on ice, CERN’s director-general Fabiola Gianotti told a small group of journalists at a recent briefing.