Russia will begin the first shipment of its S-300 air defence missile systems to Iran in the coming days.

The United States would use its veto power in the UN Security Council to block any sale of Su-30 fighter aircraft to Iran, Thomas Shannon, the US Under Secretary of State for Political Affairs, said on Tuesday.

“We would block the approval of fighter aircraft,” he told a US Senate Foreign Relations Committee hearing, noting that any such sale would have to be approved by the Security Council.

Shannon also said Russia is complying with its commitments not to transfer ballistic missile equipment to Iran.

“We’ve got a commitment … from the Russians in terms of working to prohibit the transfer of technologies to Iran’s ballistic missile program,” Shannon said, adding: “… They are complying with their commitment not to transfer these kinds of technology or to facilitate the transfer.”

The Obama administration is also open to renewing the Iran Sanctions Act, which expires at the end of 2016, if it does not interfere with the international nuclear agreement with Tehran, Shannon said.

“We would be happy to engage with this committee and the Congress on a renewed Iran Sanctions Act, assuming that it does not complicate or prevent us from meeting JCPOA (Iran nuclear deal) commitments,” he said.

Earlier, an Interfax news agency quoted a senior Russian diplomat as saying on Tuesday that Russia will begin the first shipment of its S-300 air defence missile systems to Iran in the coming days.

“I don’t know if this will happen today, but they (S-300 missiles) will be loaded (for shipment to Iran),” the agency quoted Zamir Kabulov, a department chief at the Foreign Ministry, as saying.

Russia cancelled a contract to deliver the advanced anti-missile rocket system to Iran in 2010 under pressure from the West following UN sanctions imposed on Iran over its nuclear programme.

Tehran agreed the deal on curbing its nuclear work in July last year and international sanctions were lifted in January. But tensions with Washington have remained high as Tehran continues to develop its military capabilities.

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