"We heard from him that there won't be anything like this (sanctions)," Erdogan told a press conference in Osaka, Japan, following a meeting with Trump on the sidelines of the G20 summit being held there.

Erdogan insisted that Turkey and the United States were "strategic partners", but also said that "no one has the power to intervene in Turkey's sovereignty".

Despite Washington's concerns and threats over Ankara's push to buy Moscow's S-400 missile defence system, Erdogan reiterated that the purchase was a "done deal".

Erdogan said the S-400 was expected to be delivered in the first half of July.

He said Turkey previously held talks with former president Barack Obama's administration for the similar Patriot system, but Congress did not allow the deal to move forward.

Washington has also threatened Turkey's removal from the F-35 fighter jet programme and, in an ultimatum, told Ankara to cancel the S-400 deal by July 31 or Turkish pilots training on the warplane would be expelled from the US.

Turkey has plans to buy 116 F-35s, Erdogan said, and its manufacturers have invested heavily in building parts of the jet.

Erdogan said Saturday Turkey had invested $1.4 billion in the production so far.

Relations between Turkey and the US have been strained over multiple issues, including American support for a Kurdish militia in Syria and the failure to extradite a Pennsylvania-based Muslim preacher blamed for the 2016 failed coup.