Anti-terrorism magistrates in Paris have filed preliminary charges against a French physicist arrested last week on suspicion of links to al-Qaeda.
The 32-year-old man of Algerian descent works at the European Organization for Nuclear Research (Cern), Europe’s main centre for studying particle physics.
He was one of two brothers detained in the town of Vienne on Thursday.
Officials said he had been in contact with people linked to al-Qaeda in the Islamic Maghreb and planned attacks.
The researcher had been working on an experiment at the Cern laboratory which houses the giant Large Hadron Collider, designed to recreate the conditions that existed just after the Big Bang. It is located on the Swiss-French border.
After his arrest, Cern was quick to stress that his job “did not bring him into contact with anything that could be used for terrorism”.