Turkey says its purchase of Russian S-400 missile defense systems is no reason to exclude the country from the U.S.-led F-35 fighter jet project.

Defense Minister Hulusi Akar's comments on May 3 came hours after the acting U.S. defense chief warned that ending Turkey's participating in F-35 production work would be one of the consequences of Ankara’s actions.

Akar also said Turkey was evaluating the latest U.S. offer to sell it, as an alternative, the U.S.-made Patriot missile defense systems -- which he said was a more positive proposal than Washington's previous offers.

Akar told Turkish broadcaster NTV that excluding Ankara from the F-35 jet project would put "very serious" burdens on the other partners in the project.

"There is no clause saying 'you will be excluded if you buy S-400s' in this partnership. Excluding us just because any one country wants so would not be in line with justice, laws, or rights. This should not happen," Akar said.

Turkey, as a NATO member, is participating in the production of the fighter jet for use by alliance militaries and has plans itself to purchase 100 of the jets.

Several Turkish manufacturers are making parts and equipment for the F-35 -- including the internally carried Stand-off Missiles, airframe assemblies, and wiring.

The United States has demanded that Ankara call off its deal with Russia, saying the S-400 missiles are incompatible with NATO systems and are a potential threat to the F-35s.

Akar said Turkey had explained to the United States and other NATO allies that Ankara had taken measures to ensure that the S-400s would not pose a threat to the F-35 jets.

Acting U.S. Defense Secretary Patrick Shanahan said on May 3 that he had met with Lockheed Martin and United Technologies Corp. last week about the possibility of moving F-35 work out of Turkey.

"If Turkey decides that the S-400 is a decision they want to go forward with, then we have to move work out of Turkey," he said.

Washington has suggested Turkey might be able to obtain the Patriot missile systems if it drops its plan to buy the Russian missiles.

Turkish President Recep Tayyip Erdogan has insisted he will buy the Russian system and says it is a done deal. Erdogan on May 1 claimed that the F-35 project would collapse if Turkey did not participate.

With reporting by Reuters and AFP