"President Medvedev promised to review this issue once again after I explained that it would have an impact on the balance of force in our region," Peres said a day after he held talks with the Russian leader.
The contract for the S-300 anti-aircraft missile systems is reported to have been signed back in 2005 but has proved hugely controversial as the weapons would significantly upgrade Iranian air defence capabilities.
Amid repeated US objections over the contract, Russian officials have emphasized over the last months that none of the S-300 systems have been delivered to Tehran.
