Russia said Thursday it would freeze the sale of S-300 air defense systems to Iran in line with new U.N. sanctions against Iran adopted a day earlier.

However, confusion has arisen with contrary statements on the same day by a parliamentary leader.

"The U.N. Security Council's resolutions are mandatory for all countries. Russia is no exception here. Naturally, the contract for the delivery of S-300 missile systems to Tehran will be frozen," the Interfax news agency quoted a source as saying.

However, the report appeared to be contradicted by the head of the International Committee of Russia's State Duma, Konstantin Kosachyov, who said Russia could still fulfill its commitment for the delivery.

"Eight items have been added to the list of armaments liable for sanctions. However, there are no defensive systems, such as S-300 missiles, on the list," said Kosachyov.

Iran struck a deal with Russia to buy S-300 systems in 2007, but Russia has delayed the delivery of the anti-aircraft missiles.

Meanwhile, Kosachyov said the new sanctions would not affect ties between Moscow and Tehran. "The resolution has no direct effect on Russia," he said, "The resolution clearly tells Iran that there is still a possibility of dialogue on certain terms."

This view, however, was not shared by Radzhab Safarov, Director of the Russian Center for Contemporary Iranian Studies. Safarov said Iranian President Mahmoud Ahmadinejad's withdrawal from the Tashkent summit of the Shanghai Cooperation Organization and the delay of the Iranian oil minister's visit to Russia could indicate Iran was unhappy with Moscow's support for the latest sanctions.

"Under earlier plans, the Iranian oil minister was to visit Moscow on June 22. A letter has arrived today, saying that the visit has been indefinitely postponed. Clearly enough, it was a diplomatic wording for a refusal," Safarov said.

The S-300 air defense system is an advanced mobile system that can shoot down aircraft and cruise missiles from up to 150 km away.

The United States and Israel oppose the sale of the missiles to Iran.

The U.N. Security Council Wednesday adopted a resolution to impose a fourth round of sanctions against Iran over its suspected nuclear weapons program.

The resolution was approved by the 15-member Council with a vote of 12 in favor. Brazil and Turkey voted against it while Lebanon abstained.