ISTANBUL: US President Donald Trump has the authority to waive sanctions on Turkey for its purchase of Russian air defence systems and should find a "middle ground" in the dispute, President Tayyip Erdogan was quoted as saying on Sunday.

Erdogan's comments came two days after NATO member Turkey took delivery of the first consignment of advanced Russian S-400 missile defence system parts, despite warnings from Washington that the move would trigger U.S. sanctions.

Broadcaster Haberturk quoted Erdogan as telling Turkish journalists that Trump "has the authority to waive or postpone CAATSA", referring to U.S. sanctions designed to prevent countries buying military equipment from Russia.

"Since this is the case, it is Trump who needs to find the middle ground," Erdogan said, according to Haberturk.

Trump expressed sympathy for Turkey's position when he met Erdogan at a G20 summit in Japan last month, saying Ankara had bought the S-400s from Moscow because the previous U.S. administration would not sell it Patriot missiles.

"Right now, I don't believe Trump is of the same opinion of those below him and he has said this in front of all world media," Erdogan said.

"By buying the S-400s, we are not getting ready for war. We are trying to guarantee peace and our national security," he added.

In addition to the threatened CAATSA sanctions, U.S. officials have said Turkey could be thrown off the F-35 stealth fighter jet programme, meaning it would no longer be part of the production process or be able to buy the jets it has ordered.

The Pentagon says the S-400s would pose a threat to the jets if they were operating in the same region. Erdogan said Turkey had orders for more than 100 F-35s and expected Washington to remain committed to the deal.