Russia has said it had successfully tested a new multiple warhead ballistic missile designed to overcome air-defence systems such as the US shield planned for deployment in eastern Europe.

The statement said: "The RS-24 reinforces the military potential of the strategic forces to overcome anti-missile defence systems."

The test comes as Russia is locked in a diplomatic battle over US plans to expand a missile defence shield into Eastern Europe, a move Moscow portrays as an attempt to tip the nuclear balance in Washington's favour.

Radar base

Sergei Ivanov, the first deputy prime minister - a former defence minister and widely seen as a potential successor to President Vladimir Putin in 2008 - said the RS-24 could overcome any such anti-missile system.

"These complexes are capable of penetrating all existing and perspective anti-missile systems.

"So from the point of view of defence and security, Russians can look at the future calmly," he was quoted as saying by Interfax news agency.

The United States says the planned radar base in the Czech Republic and 10 interceptor missiles in neighbouring Poland would defend Europe against potential threats from Iran and North Korea, while posing no threat to Russia.