One of two suspected al-Qaeda collaborators arrested by French police on Thursday was a researcher connected to the European Organization for Nuclear Research (Cern).
The suspect "is a physicist who had been working on analysis projects on the LHCb experiment at Cern since 2003," the organisation said in a statement on Friday.
"He was not a CERN employee and performed his research under a contract with an outside institute. His work did not bring him into contact with anything that could be used for terrorism."
Cern, a joint project backed by 20 member states, has sites on the border of Switzerland and France. It is best known for the Large Hadron Collider, the world's largest particle accelerator.
The two Algerian brothers arrested in the town of Vienne in southeastern France on Thursday are suspected of being close to Al-Qaeda in the Islamic Maghreb (AQIM), also known as Al-Qaeda's north African wing.
Le Figaro newspaper had reported that the older brother had been in contact with AQIM and had suggested several French targets for attacks.
AQIM claimed responsibility for a suicide bombing at the French embassy in Mauritania that wounded three people in August.
swissinfo.ch and agencies