BERN, Nov 1: Swiss authorities are investigating possible espionage by the United States after the CIA allegedly tried to obtain details on members of Switzerland's second largest trade union, the federal prosecutor's office said on Wednesday.

A Swiss newspaper, Blick, reported last week that the data sought by an agent based at the US embassy in the Swiss capital, Bern, allegedly related to members with Arab nationality.

The Federal Prosecutor opened a police investigation against unknown persons on Sept 12, on the basis of laws against espionage by a foreign state, said Jeanette Balmer, a spokeswoman for the office.

The police probe was able to `corroborate the suspicions’ and identify those who were involved, she added. Balmer declined to give further details.

The trade union, Syna, said in a statement that the US Central Intelligence Agency had tried unsuccessfully to gain access to membership data through an outside contractor.

Balmer said that under the law, the federal prosecutor now needed the Swiss government's permission to bring the case to court. Normally the initial stage would involve an investigating magistrate.

Syna's president, Kurt Regotz, said the union was first informed of the affair by Swiss federal police last week.A newspaper was looking into the affair, but we didn't know that it had anything to do with us last week, Regotz said.

It was an amateurish attempt by the US intelligence services to obtain data, Regotz said. We have since been able to have information on how federal police knew... and we have no doubt about it, he added.

The union delivered an official protest to the US embassy in Bern on Tuesday, calling for the diplomat allegedly involved to be sent home to the United States and for a `complete halt’ to CIA `snooping’.

They told us they are taking our complaint seriously and will give us an answer, Regotz said.

The justifiable struggle of the United States against international terrorism does not allow it to violate personal privacy laws and to conduct illegal spying on trade unions, Syna added in the statement.

Syna officials said they could not understand why US intelligence would want details on `workers living in Switzerland’, but speculated that the attempt might have been linked to the union's congress last weekend, which debated globalisation.

The tabloid daily, Blick, last week published a photograph it said showed the alleged CIA spy waiting at a bus stop in Bern.—AFP