The suspect and his 25-year-old brother, both French nationals, were arrested Thursday in the town of Vienne in southeastern France. US intelligence had intercepted e-mails between the man and people tied to the branch of al Qaeda in the Maghreb states of North Africa. His brother was released at the weekend without charge.

According to authorities, the man had expressed a desire to carry out attacks, but had "not reached the stage of carrying out material acts of preparation."

A weekend report in the newspaper Le Figaro said that the suspect is a Frenchman of Algerian origin who had been the subject of an investigation for 18 months.

In the intercepted e-mails, which he has reportedly admitted sending, the suspect described plans for terrorist attacks in France. But these plans were apparently not connected with his work at the European Organization for Nuclear Research (CERN). In an attempt to curtail public suspicion about the underground research center, CERN issued a statement saying that the suspect was never in contact with material that could be used in an attack.

Studying the Big Bang

The suspect was studying the Big Bang at CERN, one of the world's leading nuclear research laboratories. The center includes the largest particle accelerator in the world: the Large Hadron Collider (LHC), a 27-kilometer (15-mile) tunnel running under the Franco-Swiss border just outside Geneva. The LHC is designed to recreate the sub-atomic conditions of the Big Bang.

According to CERN's website, the suspect's experiment was "set up to explore what happened after the Big Bang that allowed matter to survive and build the universe we inhabit today."

The CERN statement added, "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."

Intelligence officials consider the Maghreb branch of al-Qaeda one of the most serious threats to France, which has a large North African population.

bk/AFP/AP/dpa
Editor: Nancy Isenson