Tehran, Oct 22 : Iranian Foreign Ministry spokesman has said Russia is one of Iran's main partners in defence sector, Iran Press news website reported. By lifting the UN arms embargo on Iran, Tehran and Moscow could improve cooperation in the sector, Saeed Khatibzadeh was quoted as saying. Iran and Russia continue their negotiations within the framework of the Joint Defence Cooperation Commission. With the removal of bans, Iran is able to purchase any military equipment and weapons without legal restrictions from "friendly countries," he said. Khatibzadeh noted that any US attempt to impose unilateral sanctions on Iran in this regard is a violation of international law and doomed to failure, Xinhua news agency reported. Under UN Security Council Resolution 2231, which endorsed the 2015 Iranian nuclear deal, the UN arms embargo against Iran expired on Sunday. However, the US administration imposed unilateral sanctions on Iran threatening other countries to avoid arms deals with the Islamic republic. /IANS