Turkey has decided to order two F-35 fighter jets built by Lockheed Martin Corp, Turkey's undersecretary for state-run defence said in a statement on Tuesday.

It would be the first order of Turkey's pre-announced plan to purchase 100 F-35 jets for $16 billion, which had been expected to begin next year.

In the statement, Turkey said its commitment to the F-35 Joint Strike Fighter (JSF) programme "continues strong as ever."

"In this context, Turkey continues her forecast of the acquisition of 100 F-35A aircraft as planned and declared previously."

The programme, the Pentagon's most expensive arms development project, is about 70 percent over budget and years behind schedule, having been plagued by technical problems.

Sceptics say it still faces big challenges, including completing the software needed to integrate weapons on the jet.