Erdogan, who is to meet Trump on the margins of G20 summit in Japan on June 28-29, said in a televised speech that before the gathering he "would like to discuss this issue by telephone and reverse it from the current situation back to where we started".

Washington has given Turkey until the end of July to abandon its purchase of a major Russian missile defence system, which it considers incompatible with Ankara's participation in the US's construction of its F-35 stealth fighters.

The Pentagon announced on Friday that if by July 31 Turkey did not give up on the S-400 system, Ankara would be blocked from purchasing F-35 fighter jets and Turkish pilots currently training in the US would be expelled.

Erdogan vowed to seek answers on Turkey's "exclusion from F-35 project for reasons that have no rational or legitimate basis", adding that Turkey was not only a customer but also a programme partner of the F-35 project.

"We have so far paid $1.250 million," he said.

Turkey plans to buy 100 F-35s.