"The US Patriot sale process does not affect the S-400 process. We don't see one as an alternative for the other," Ibrahim Kalin said.

The US State Department on December 19 said it had informed Congress of plans to sell a package including 80 Patriot missiles, and 60 PAC-3 missile interceptors and related equipment to Turkey.

Turkey's plans to buy the Russian S-400s has drawn rebuke from its NATO allies with the United States warning that the purchase jeopardised participation in the F-35 fighter jets programme.

Turkish officials have previously said it "needs" the S-400 missile defence system and repeatedly stressed that Ankara would buy systems from allies if they had sold them.

Turkish media has reported that the first delivery from Russia will be in 2019.

The S-400 order is seen as one of the key symbols of Turkey's closer relationship with Russia under Erdogan and Russian counterpart Vladimir Putin.

The two men have also worked closely on finding a political solution to the seven-year Syrian war despite being on opposing sides of the conflict.

Turkey has provided support to Syrian rebels and called for Syrian President Bashar al-Assad's ouster while Russia's intervention in 2015 helped his Damascus regime recapture swathes of the country.