Tehran is hoping that an international court will rule in favor of Iran over the legality of the supplies of Russian S-300 air defense systems under a 2007 contract, Iranian Ambassador to Russia Mahmoud-Reza Sajjadi said on Wednesday. "When this happens, Russia will have legal grounds to fulfill its obligations under the S-300 delivery contract [with Tehran]," Sajjadi said in an interview with RIA Novosti. The contract to supply Iran with the missile system was signed at the end of 2007. Russia was to supply five battalions of S-300PMU-1 to Tehran worth $800 million. The Kremlin banned the sale of S-300s to Iran in September last year, saying they were covered by the fourth round of sanctions imposed by the UN Security Council against Iran over its nuclear program. Iran filed a lawsuit with the International Court of Arbitration in the beginning of 2011 to prove the deliveries of S-300, which is considered a defensive system, were not subject to an arms sales ban under UN Resolution 1929. Russia will pay back Iran's $166.8 million initial payment on the contract if the court rules that the S-300 deliveries do fall under UN sanctions.