The U.S. State Department spokeswoman, said in a statement that McGurk "has the full support and backing" of U.S. Secretary of State Rex Tillerson and the White House, and that he had done "tremendous work" so far to coordinate the coalition on May 19.

Axar.az reports citing Hurriyet news.

Turkish Foreign Minister Mevlut Cavusoglu said on May 18 that Brett McGurk, the U.S. special envoy to the coalition against the Islamic State of Iraq and the Levant (ISIL), should be removed from his post as he “supports terrorist groups.”

Heather Nauert, spokeswoman said in her statement that the United States respects Turkey's concerns about its approach, and will continue regular consultations on the issue.

"It is critical that we are closely linked with partners on the ground to coordinate both military and civilian efforts to sustain momentum and focus against ISIS," Nauert said.

Meanwhile, McGurk said Turkey was a close ally in fight against ISIL, coalition can't succeed without Turkey on May 19.

On May 18, “Brett McGurk, the U.S.’s special envoy in the fight against Daesh [ISIL], is definitely and clearly giving support to the [outlawed Kurdistan Workers’ Party] PKK and the [Syrian Kurdish People’s Protection Units] YPG. It would be beneficial if this person was changed,” Cavusoglu said.

He was speaking in an interview with private broadcaster NTV after returning from an official visit with President Recep Tayyip Erdoğan to Washington, where they met U.S. President Donald Trump.

Ankara regards the YPG, which is a U.S. ally in the fight against ISIL, as an organic extension of the PKK.

“These people should not poison the new administration. This could create risks and requires caution. We did not convey it to the [Trump] administration in this way but we told them – without giving names – that those who keep their positions may affect our relationship,” Cavusoglu said.

His words came on the same day as McGurk was seen in a picture taken in northern Syria with a number of PKK militants currently being sought by Turkey through Interpol. McGurk, known as the mastermind of the U.S. plan to work with the YPG in defeating the jihadists in Syria, was appointed as the anti-ISIL coordinator by the Obama administration before the Trump administration asked him to remain in his position.