Ankara, Jul 12 (IANS): First shipment of Russian S-400 missile defence system hardware to Turkey started on Friday, the country's Defence Ministry has announced.

"First batch of equipment of S-400 missile defence system, which is procured to meet Turkey's air and missile defence need, has started to arrive at Murted Air Base in Ankara," the Ministry said on Twitter.

Following protracted efforts to purchase an air defence system from the US with no success,

Ankara signed the supply contract in April 2017 to purchase the Russian S-400s, the state-run Anadolu News Agency reported.

US officials urged Turkey to buy American Patriot missiles, arguing the Russian system would be incompatible with NATO systems.

Turkey, however, emphasized the S-400 would not be integrated into NATO systems and would not pose a threat to the alliance.

Turkey has urged formation of a commission to clarify any technical issues, but the US has failed to respond to this proposal.