Several days after the US Embassy in Istanbul ordered the families of employees to depart, and advised U.S. citizens to avoid travel to southeast Turkey and "carefully consider the risks of travel to and throughout the country", Turkey has responded by warning its citizens on Saturday about travel to the United States, in response to what the foreign ministry called "increasingly violent protests against President-elect Donald Trump."

"Within the context of risks caused by the incidents and of social tension, our citizens who live in the U.S., or who are considering traveling there, should be cautious," the ministry said in a statement.

The advisory said the unrest began after Tuesday's elections: "Sometimes the protests turn violent and criminal while protesters (are) detained by security forces," the ministry of foreign affairs said Saturday, adding that "racists and xenophobic incidents increased in USA."

"Considering the risks, we advise our citizens living and traveling to US to follow local media, to follow the warning of our embassy in Washington and American security forces, to stay away from protests, to increase their security in work space and to apply to local security when there is a racist or xenophobic attack while keeping calm," the statement added.

Demonstrators across America, some allegedly funded by George Soros-linked organizations, have staged four consecutive nights of protests against Trump, whose election they say poses a threat to their civil and human rights, a day after a protester was shot in Portland, Oregon.

At the same time, there has been growing tension between the two NATO allies after repeated calls from Turkey to extradite U.S.-based cleric Fethullah Gulen, who Ankara blames for a failed coup in July.

Turkish Prime Minister Binali Yildirim said on Wednesday he hoped for an improvement in bilateral ties after Trump's victory, and again called for Gulen's extradition.