India signed a $5 billion deal for S-400 missiles in 2018, drawing warnings from the United States that such an acquisition would trigger sanctions as part of a wider program against Russia.

Moscow: Russia will begin delivering S-400 surface-to-air missile systems to India by the end of 2021, agency RIA Novosti on Wednesday quoted a Russian official as saying.

India signed a $5 billion deal for S-400 missiles in 2018, drawing warnings from the United States that such an acquisition would trigger sanctions as part of a wider programme against Russia.

"The contract is being implemented on schedule. The first shipment is due by the end of 2021," Deputy Director of the Federal Service for Military-Technical Cooperation (FSMTC), Vladimir Drozhzhov, said at Defence Expo 2020 in Lucknow, India, according to RIA.

In November, the same agency cited the general director of Russian state arms exporter Rosoboronexport, Alexander Mikheev, as saying deliveries would start in September 2021.