ANKARA, April 5 (Xinhua) -- Turkish Defense Minister said that three of the four F-35 fighter jets had been delivered by the United States and the last one is expected to be transferred on Friday.

Ankara is continuing negotiations with Washington amid a dispute over Turkey's purchase of Russian S-400 missile defense system, Hulusi Akar told state-run Anadolu Agency on Friday.

On Monday, the Pentagon announced that it halted "deliveries and activities" related to Turkey's procurement of the F-35 fighter jets if Ankara insisted on the S-400 deal.

Two F-35s already delivered to Turkey are currently at the base where Turkish pilots are being trained.

Turkish President Tayyip Erdogan refused to get back down from the planned procurement of Russian S-400 missile despite of Washington's threatening to impose sanctions.

Erdogan on Friday slammed "really wrong" statements from the United States over the S-400 purchase and underlined that NATO allies should not sanction each other.