A French physicist with the European atomic research centre near Geneva was charged with terrorism offences by a Paris judge last night after investigators said that he offered to work with the North African branch of al-Qaeda.

Adlène Hicheur, 32, who is of Algerian origin, was arrested last week with his younger brother after intelligence agents intercepted his alleged internet contacts with al-Qaeda in the Islamic Maghreb.

The physicist, who works at the giant atomic collider at CERN (European Organisation for Nuclear Research), which straddles Swiss and French territory, told the Islamic group that he was interested in committing an attack but had not begun any material preparation, according to police sources. He had acknowledged contacting the militant organisation, they said.

The brother was released last weekend without charge.

Judge Christophe Teissier, of the anti-terrorist branch, ordered the French internal security service, the DCRI, to open an investigation into the possible offence of “association with criminals in relation with a terrorist enterprise”. Judge Teissier placed the scientist under formal investigation and ordered his detention.

The arrest raised the possibility that Islamist militants could be seeking nuclear weapons technology or planning to attack nuclear targets.

Dr Hicheur is reported to have worked for the British Government’s Rutherford Appleton Laboratory (RAL) in Oxfordshire for about a year in 2005. He was placed under surveillance by French officers last year after US intelligence services intercepted internet messages he allegedly sent to contacts close to al-Qaeda in the Islamic Maghreb (Aqim).

However, his arrest last week has sparked a furious row among France’s anti-terrorist magistrates. Judge Teissier’s critics say that he missed an opportunity to obtain invaluable information about Aqim networks by moving to detain the suspect at an early stage in his investigation. They said that he should have held off and kept the man under surveillance.

Brice Hortefeux, the French Interior Minister, is also being criticised for publicising the arrest. Detractors say that the publicity will have driven the suspect’s contacts underground.

CERN said that Dr Hicheur, one of 7,000 scientists working on the Large Hadron Collider, did not have access to any of the underground facilities and did not handle anything that would interest terrorists.

A spokesman described him as highly qualified: “This fellow has a doctorate in particle physics, so he is clearly an intelligent person,” he said.

The scientist also worked as an instructor in experimental physics at the Swiss Federal Institute of Technology in Lausanne. “We are pretty shocked and surprised,” said Jerome Grosse, spokesman for the institute.

Residents in the suspect’s home town of Vienne, in eastern France, said that his success had made him a role model for young Muslims. “They are good boys,” said one neighbour of the suspect and his brother. “They are from a family of six children and from a very moderate Muslim family which is seen as a model of integration.”

The suspect’s brother is reported to have graduated from the University of Paris with a degree in biomechanics. After graduating, he taught at the 500-year-old Collège de France in Paris — one of the country’s most prestigious research institutes.

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