Russia's Foreign Ministry has stated the deliveries of anti-aircraft missile systems to Iran, being criticised by Washington did not violate international law. Comments come after the U.S. threatened sanctions against Russia.

Moscow says the sale was completed before the UN sanctions came into force.

Russia signed an arms deal with Iran at the end of 2005, promising to supply 29 Tor-M1 missile systems, a precision anti-aircraft weapon. It can simultaneously detect dozens of targets, and attack 2 of them at high altitudes.

The deal has angered the U.S., but Russia says deliveries to Iran were completed by December 2006.

The same month the UN Security Council passed a revised resolution imposing sanctions on Iran, for refusing to stop enriching uranium – a programme Tehran insists is for peaceful purposes only.

The U.S. claims Russia has violated the terms of these sanctions by seeing through this arms deal but Russia is insistent this is not the case.

“We have supplied Iran with Tor M1’s. They’re designed for purely defensive purposes. We haven’t violated any UN sanctions. If the U.S. wants to impose sanctions it’s up to them,” Sergey Chemezov, the head of Rosoboronexport company stated.

And experts say this isn't the first time the U.S. has sought to impose sanctions against Russia.

The IAEA is due to report to the UN Security Council on Iran’s compliance with the sanctions in February.

The U.S. have already said if Iran is not complying, it will have to face up to tougher sanctions.