Australian serious crime squad investigate after Wembley main contractor is targeted in international extortion plot.

There are reports in the Australian media that Multiplex, the country's biggest construction company, has been targeted by extortionists who threatened that snipers would shoot crane drivers on sites around the world if they did not receive millions of Australian dollars within 24 hours.

Television network Channel Nine reported that the threat was "international", although this was not confirmed by the Australian police. Multiplex is the main contractor at the new Wembley Stadium being built in north London.

A police spokesperson said: "The threat against Multiplex is considered serious and officers are working closely with the company, staff and relevant unions to resolve the situation. Detectives from the State Crime Command's robbery and serious crime squad are conducting this investigation."

Although police would not confirm a reported link between the extortion bid and the Russian Mafia, the spokesperson added that the possibility the bid was an elaborate hoax had not been ruled out.