The Swiss authorities have confirmed that four people suspected of having ties with Corsican separatists were questioned by a French judge in canton Jura last November.
A spokesman for the Swiss prosecutor's office said the four, including a former member of the Jurassian separatist movement, Groupe Bélier, were questioned in the presence of Swiss police officials.
He said the hearings were made possible after Switzerland accepted a French request for judicial cooperation last October.
The spokesman added that Gilbert Thiel, the French judge conducting the questionings, was looking for new elements concerning a 1997 bombing in Strasbourg.
The former Groupe Bélier member said Thiel had questioned him for seven hours, but said he was not under investigation. He said Thiel was merely seeking information.
The man has close ties with Corsica's independence movement, and was a witness in the murder trial of France's representative on the island, Claude Erignac, two years ago. His testimony cleared accusations against his friend, Jean Castela, a suspect in the case.
swissinfo with agencies