The value of contract to deliver Russian S-400 air defense missile systems to Turkey stands at $2.5 billion, the head of the state corporation Rostec, Sergei Chemezov, said in an interview with the Kommersant daily.

"Yes, the deal is [worth] $2.5 billion," he said, answering a reporter’s question.

He said the first deliveries of the S-400 air defense missile systems to Turkey will begin in March 2020.

"We plan to begin first deliveries in March 2020," he said.

According to the official, the finance ministries of Russia and Turkey have already completed negotiations on the issue. "The only thing left is to approve the final documents," he said.

"I can say that they will pay 45% of the overall contract value as an advanced payment, and 55% will be a loan from Russia," Chemezov said.

Chemezov said that Turkey will become the first NATO member purchasing the advanced S-400 system.

"We are also at the final stage of negotiations to supply those systems to Saudi Arabia. In general, we have paid great attention to cooperation with the Middle East, huge work was done to implement an array of joint projects in the Persian Gulf states," he added.

Turkish President Recep Tayyip Erdogan said on September 12 that Ankara had inked a deal with Moscow on the purchase of S-400 surface-to-air missile systems and had made an advance payment.

Russia’s S-400 Triumf is the latest long-range antiaircraft missile system that went into service in 2007. It is designed to destroy aircraft, cruise and ballistic missiles, including medium-range missiles, and can also be used against ground targets.

The S-400 can engage targets at a distance of 400 km and at an altitude of up to 30 km.