MOSCOW, June 3. /TASS/. The supplies of Russia’s S-300 air defense system to Iran is due soon, Russian Foreign Minister Sergey Lavrov told the media following talks with his Iranian counterpart Javad Zarif on Thursday.

Lavrov said that the theme of S-300 systems was not discussed.

"We merely stated that preparations for the delivery are underway and the deal will be effected soon," he said.

In early April, six world powers confirmed significant progress after talks with Iran on the nuclear program in Lausanne, Switzerland. Russian President Vladimir Putin lifted the ban on the S-300 supplies to Iran on April 13.

Iran filed a $4 billion lawsuit against Rosoboronexport in an international arbitration court in Geneva in April 2011 after Russia suspended the 2007 contract on the supplies of S-300 missile systems to Iran.

Under the 2007 contract, Moscow pledged to deliver to Tehran five battalions of medium-range air defense systems S-300 worth $800 million. Iran made an advance payment of $166.8 million. No supplies followed up to the middle of 2010.

In September 2010, Russia’s then-president Dmitry Medvedev signed a decree on measures to implement the UN Security Council’s Resolution 1929 of June 2010 to prohibit the supplies of S-300 to Iran. The contract was annulled and the advance payment was returned to Iran.