Russia should keep its word on selling a missile defence system to Iran, an influential parliamentarian was quoted by Iranian media as saying on Sunday.

Moscow, which is under Western pressure to distance itself from Tehran, has not followed through on proposals to supply high-grade S300 air defence missiles to the Islamic state.

U.S. Secretary of State Hillary Clinton praised Russia last month for failing to provide the arms to Iran, which is at odds with the West over its nuclear and missile programme.

Washington has sought specific pledges from Russia for tougher sanctions against Iran over its nuclear energy programme, which the West suspects is intended to produce nuclear weapons. Tehran denies any such intention.

"If Russia does not keep its promises to deliver the missiles, then it would be a negative point in our relations," Alaeddin Boroujerdi, head of parliament's foreign policy and national security committee, said in comments carried by official news agency ISNA.

"Avoiding delivery of S300 defence system to Iran, if that is Russia's official stance, would be a new chapter in breaking promises by the Russians."

Russian Deputy Prime Minister Sergei Ivanov said last month "there have been no such deliveries to date".

The truck-mounted S-300PMU1, known in the West as the SA-20, can shoot down cruise missiles and aircraft. It can fire at targets up to 150 km (90 miles) away and travel at more than two km per second.

Israel, which is thought to have the Middle East's only atomic arsenal, has hinted it could attack Iran in an effort to stop its arch enemy obtaining nuclear weapons.

Iran has threatened to retaliate for any attack by firing medium-range missiles at Israel.