Previously published comments made by Joe Biden criticising Turkey's president resurfaced in a video which made him the most popular topic on Twitter in the country, where Recep Tayyip Erdogan has governed for 17 years.
In December, the US Democratic presidential contender told the New York Times that the US should take a new approach to the "autocrat" President Recep Tayyip Erdogan and support opposition parties in Turkey.
While the comments were published in the New York Times in January with little reaction AFP reported, a video of the remarks only appeared on Saturday before going viral on social media.
Mr Biden, the former US vice president, says in the video he is "very concerned" about Mr Erdogan's approach to Kurds in Turkey, his partial military co-operation with Russia, and access to US airfields in the country, a NATO ally.
"What I think we should be doing is taking a very different approach to him now, making it clear that we support opposition leadership," Mr Biden said in the video and verified by a transcript published in January by the Times, according to Reuters.
"He has to pay a price," Mr Biden said at the time, adding Washington should embolden Turkish opposition leaders "to be able to take on and defeat Erdogan. Not by a coup, not by a coup, but by the electoral process."
After the video trended on Twitter, the Turkish president's communications director Fahrettin Altun said the comments "reflect games and an interventionist approach towards Turkey" and are inconsistent with current diplomatic relations.
"Nobody can attack our nation's will and democracy or question the legitimacy of our President, who was elected by popular vote," Mr Altun said on Twitter, noting the failed coup in Turkey in 2016.
"We believe that these unbecoming statements, which have no place in diplomacy by a presidential candidate from our Nato ally, the United States, are unacceptable to the current administration too," he added.
There was no immediate response from the Biden campaign, Reuters said.
While US President Donald Trump and Mr Erdogan speak regularly, diplomatic relations have been strained over Ankara's purchase of Russian air defences, policy in Syria and over US charges against a Turkish state bank for allegedly helping Iran evade sanctions.
Turkey's main opposition party won a handful of big city elections last year in a stinging defeat for Mr Erdogan and his ruling AKP, which polls show still has the most support nationwide.
Mr Biden made the comments on December 16, 2019, before he emerged as the Democratic candidate.
