(adds background, details on Pantsyr system in paragraphs 5-8)

MOSCOW, May 23 (RIA Novosti) - Russia did not approve the alleged sale of its Pantsyr-S1 mobile air defense system from Syria to Iran, a first deputy prime minister said Wednesday.

"We have received no requests from Syria for supplies to Iran, not a single bullet," Sergei Ivanov said at a news conference in Moscow.

Media earlier reported that Damascus had agreed to sell some of the Pantsyr short-range air defense missile-gun systems it is buying from Russia to Tehran.

"Russia engages in military-technical cooperation with all states that strictly abide by international law... For any arms that Russia sells to its foreign partners, contracts are signed only after the receipt of a certificate from the end user. These weapons cannot then be re-exported and supplied to third countries without the permission of the seller, in this case the Russian Federation."

During last summer's conflict between Israel and the Lebanon-based radical group Hezbollah, media widely reported that Hezbollah fighters had obtained Russian weapons via Syria and Iran. The Israeli leadership has repeatedly expressed its concern over Russian arms landing in the hands of militants.

The head of the KBP Instrument Design Bureau, which manufactures the Pantsyr-S1, said last year the company had concluded $2.6 billion worth of contracts for the delivery of the Pantsyr-S1 system to other countries.

The system combines two 30mm anti-aircraft guns and 12 surface-to-air missiles, and can simultaneously engage two separate targets, ranging from aircraft to missiles and guided bombs.

The system will replace the Tunguska M1 complex in the Russian military following the successful completion of testing. Russia has also signed Pantsyr S1 sales contracts with the United Arab Emirates (UAE), Jordan, Syria, and is currently in talks with Algeria on the deliveries of the highly sought-after system.