A senior Russian official says Moscow has started delivering S-300 air defense missile systems to Iran.

Deputy Prime Minister Dmitry Rogozin, who spoke on Monday on Ekho Moskvy radio, wouldn't say how many systems have been delivered or provide any other specifics.

In 2010, Russia froze a deal to supply the advanced long-range missile systems to Iran, linking the decision to U.N. sanctions. President Vladimir Putin lifted the suspension last year following Iran's deal with six world powers that curbed its nuclear program in exchange for relief from international sanctions.

Rogozin said Iran will now drop its lawsuit at a court in Geneva seeking damages for the suspension of the original deal.

The S-300 deal has long worried the U.S. and Israel, which see it as destabilizing.