Berlin has circulated an alert about the scam to several German firms, Focus magazine reports in its Monday edition.

"Leading-edge (German) technology sold in a completely legal fashion to Russian enterprises and research institutes has been transmitted immediately to Iranian and Syrian workshops manufacturing missiles," the magazine said, quoting from a warning letter to "numerous German enterprises".

Iran used German measuring instruments and propulsion and control systems in its Shahab-3 missile, which with its 3,500-kilometre (2,175-miles) range could strike European targets with nuclear warheads, the magazine reported.

Meanwhile, Syria exploited German technology to modernise its obsolete Scud missiles, which pose a threat to Israel.

The government warning named 15 firms or institutes in Moscow, St Petersburg and Samara, including Moscow's State Technical University, linked to the racket.

Exportation of weapons and associated parts are subject to stringent laws in Germany, with all sales subject to government approval.

In April, three executives of a firm in Thuringia, eastern Germany, were arrested for supplying Iran with missile-launching technology, Der Spiegel magazine reported.

The German federal prosecutor said the firm in 2000 and 2001 delivered documents allowing "enemy countries" to develop missile-launching systems.

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