Quoting unnamed sources, RIA Novosti said Wednesday that Moscow and Tehran were discussing the sale of the advanced S-300 surface-to-air missile system.
"Moscow has earlier met its obligations on supplying Tor-M1 systems to Iran and is currently implementing a contract to deliver S-300 systems," the source said according to RIA Novosti.
The Tor-M1 is a short-range surface-to-air missile system.
The report comes amid mixed media reports regarding the existence of an actual S-300 missile deal between Russia and Iran.
Russian Foreign Minister Sergei Lavrov commented on the issue in October, saying that Moscow would not sell the S-300 to countries 'in volatile regions'.
However earlier in the day, a senior Russian official said military cooperation between Moscow and Tehran would continue to ensure stability in the Middle East.
"Military-technical cooperation (arms sales) between Russia and Iran has a positive influence on stability in this region," Alexander Fomin, deputy head of the Federal Service for Military-Technical Cooperation, said Wednesday.
The advance version of the S-300 system, the S-300PMU1 (SA-20 Gargoyle), can intercept 100 ballistic missiles and aircraft at once, at low and high altitudes within a range of over 150 km.
According to intelligence officials familiar with the defense capabilities of the S-300, the missile system would effectively rule out the possibility of an Israeli war on Iran.
Earlier on Tuesday Israel said it would send the head of political military policy in its Defense Ministry, Major General Amos Gilad, to try to press the Kremlin not to supply Iran with S-300 missile defense systems.
Israel and its close ally the United States accuse Iran of seeking a nuclear weapon, while they have never presented any corroborative document to substantiate their allegations. Both Washington and Tel Aviv possess advanced weapons of mass destruction, including nuclear warheads.
Iran vehemently denies the charges, insisting that its nuclear program is for peaceful purposes only. Tehran stresses that the country has always pursued a civilian path to provide power to the growing number of Iranian population, whose fossil fuel would eventually run dry.
Speculation that Israel could bomb Iran has mounted since a big Israeli air drill in June. In the first week of June, 100 Israeli F-16 and F-15 fighters reportedly took part in an exercise over the eastern Mediterranean and Greece, which was interpreted as a dress rehearsal for a possible attack on Iran's nuclear installations.
Iran has, in return, warned that it would target Israel and its worldwide interests in case it comes under attack by the Tel Aviv.
A US attack on the Syrian village of Sukkariyah on October 26, has also raised speculation about the likelihood of a US unilateral strike on the Islamic Republic.
The United States has also always stressed that military action is a main option for the White House to deter Iran's progress in the field of nuclear technology.
Iran has warned it could close the strategic Strait of Hormoz if it became the target of a military attack over its nuclear program.
Strait of Hormoz, the entrance to the strategic Persian Gulf waterway, is a major oil shipping route.
Meantime, a recent study by the Institute for Science and International Security (ISIS), a prestigious American think tank, has found that a military strike on Iran's nuclear facilities "is unlikely" to delay the country's program.
The ISIS study also cautioned that an attack against Iran would backfire by compelling the country to acquire nuclear weaponry.
Intensified threats by Tel Aviv and Washington of military action against Iran contradict a recent report by 16 US intelligence bodies which endorsed the civilian nature of Iran's nuclear plans and activities.
Following the US National Intelligence Estimate (NIE) and similar reports by the IAEA head - one in November and the other one in February - which praised Iran's truthfulness about key aspects of its past nuclear activities and announced settlement of outstanding issues with Tehran, any effort to impose further sanctions or launch military attack on Iran seems to be completely irrational.
The February report by the UN nuclear watchdog, the International Atomic Energy Agency, praised Iran's cooperation in clearing up all of the past questions over its nuclear program, vindicating Iran's nuclear program and leaving no justification for any new UN sanctions.
The UN nuclear watchdog has also carried out at least 14 surprise inspections of Iran's nuclear sites so far, but found nothing to support West's allegations.
Following the said reports by the US and international bodies, many world states have called the UN Security Council pressure against Tehran unjustified, demanding that Iran's case be normalized and returned from the UNSC to the IAEA.