Seven people of North African origin are being held on suspicion of plotting to attack an Israeli El Al airliner in Switzerland, the Swiss Attorney General's office said on Thursday.
The Attorney General's office gave no details as to what kind of attack was planned or where it was intended to take place. It also said no explosives had been found.
The group of suspects arrested in Switzerland had been in contact with other groups of suspects in France and Spain which have also been uncovered by the police, it added.
"The inquiry has ... made it possible to show that this cell had very seriously envisaged committing an attack in our country on an airliner belonging to the El Al airline," said the statement.
El Al operates regular scheduled flights from Tel Aviv to Zurich and to Geneva.
Yedioth Ahronoth newspaper reported last month that Swiss and French intelligence agents had foiled a plot to shoot down an El Al plane over Geneva in December using a rocket-propelled grenade.
A senior Israeli security official declined comment on the arrests in Switzerland but said: "Past experience and intelligence received from time to time underscore efforts by terror groups to attack Israeli targets abroad."
One of the Swiss suspects was in touch with an Algerian, known as Mohamed Achraf, who was extradited to Spain last year.
'Individuals have been detained'
Swiss news Web site Swiss Info said Achraf was arrested in Switzerland and was the suspected mastermind of a plot to attack a court building in Madrid.
A first round of arrests was made near Zurich and Basel on May 12. These were followed by more arrests in other parts of Switzerland.
The suspicions of the police were first aroused after a series of robberies was committed early last year by what the Attorney General's office described as a highly organized group of about a dozen people.
An investigation revealed that "a part of the stolen booty was transferred for the benefit of a terrorist organization," said the statement.
French police confirmed that they had been involved in a joint anti-terrorist operation with Swiss and Spanish police.
"An operation took place which led to arrests in several countries," a police spokeswoman said.
"Individuals have been detained for questioning in France and operations are continuing," she said, giving no further details.