ANKARA, May 27 (Xinhua) -- Turkish Defense Minister Hulusi Akar on Monday dismissed reports that the United States had issued an ultimatum for Turkey to end its purchase of Russian S-400 air defense missile systems in two seeks.

In an interview with local broadcaster Haberturk, Akar said Turkey has not been given any such deadline, while refusing to reveal possible measures Turkey would take in case of the U.S. potential sanctions.

The CNBC broadcaster reported last week that Washington had given Ankara just over two weeks to give up its S-400 deal with Russia or risk severe penalties and lose the possibility of buying U.S. F-35 fighter jets.

"We are carrying out activities in a way that will completely fulfill the responsibilities on us," Akar said, adding Turkey had made full payment for F-35 fighter jets to Washington.

The United States threatens to suspend the delivery of the F-35 fighter jets and slap sanctions if Turkey continues with the purchase of the S-400s.

The first batch of S-400s is expected to be delivered to Turkey in July.