ANKARA: Turkey on Wednesday warned the United States against taking the "wrong steps" after the US State Department said there would be consequences if Ankara bought Russia's S-400 missile defence system.

"We are inviting the US to avoid taking the wrong steps which would exclude diplomacy and dialogue and harm relations," the foreign ministry said in a statement.

It comes after the US renewed its warning to Ankara that there would be "real and negative" consequences if it completes the purchase of the S-400.

"Those consequences include participation in the F-35 program," State Department spokeswoman Morgan Ortagus told reporters on Tuesday.

She said that Turkish officials were fully aware of the Countering America's Adversaries Through Sanctions Act, a law passed by Congress in 2017 that mandates sanctions for any "significant" purchases of weapons from Russia.

President Recep Tayyip Erdogan had said after meeting US counterpart Donald Trump last month that he was confident Turkey would not face sanctions for buying the S-400.

The Turkish foreign ministry said the State Department warning did "not match the content and the spirit" of the Trump-Erdogan meeting on the margins of the G-20 summit in Japan.

"The conditions that prompt Turkey to acquire S-400 are apparent," it added.

Trump, after meeting Erdogan, appeared convinced by the Turkish leader's assertion that former president Barack Obama did not allow Ankara to buy Patriot missiles.

"You can't do business that way. It's not good," Trump said.

Washington has threatened to remove Ankara from its F-35 fighter jet programme, giving Ankara until July 31 to cancel the S-400 purchase or have its pilots kicked off the training course and expelled from the US.

Turkey has proposed to form a working group with the US to address the issue. "But we have not yet received a response to our proposal," the ministry said. —AFP