A spokesman for the Public Ministry of the Confederation Hansjuerg Mark Wiedmer said that besides the two Swiss, other unknown individuals were under investigation.

He said the goverment's inquiries were based on suspicions that the law on military equipment and control of merchandise had been broken -- in other words there had been a possible illegal traffic in material that could be used for the development of a nuclear weapons programme.

The probe is separate from one being conducted in Germany, where another Swiss, known only as Urs T., was arrested last week on suspicion of involvement in a bid to smuggle nuclear equipment and know-how to Libya.

M.Wiedmer did not say whether Urs T. was under investigation in Switzerland.

The Swiss inquiry comes after the state economy secretariat sent a file to the ministry at the end of last month, following inquiries into three Swiss and a German living in St Gallen in eastern Switzerland.

The four were suspected of involvement in secret nuclear programmes run by Libya and Iran. Their names featured on a list of 15 sent at the start of the year to the secretariat by the International Atomic Energy Agency.

At the request of the German authorities searches were carried out last month at two Swiss businesses suspected of illegally exporting technological equipment capable of being used in the manufacture of nuclear weapons.

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