The Interfax news agency cited Sergei Chemezov, head of state conglomerate Rostec, as saying on Sunday that the deal is likely to be signed in the near future.
Turkey bought a batch of the missile systems from Russia last year, leading to its suspension by Washington from the US F-35 stealth fighter jet program. The United States has said that Turkey risks US sanctions if it deploys the Russian-made S-400s.
In 2017, Russia and Turkey finalized a deal worth about 2.5 billion US dollars to supply Ankara with S-400 systems, and delivery was completed in 2019.
Turkey is the first member of the North Atlantic Treaty Organization to purchase such air defense missile system from Russia.
The S-400 missile system is considered the most advanced of its kind in Russia, capable of destroying targets at a distance of up to 400 kilometers and a height of up to 30 kilometers.