Turkish President Recep Tayyip Erdogan said on Tuesday the U.S. administration has made "a serious mistake" by demanding that Turkey agree to protect the United States' Kurdish ally, the YPG militia, which Ankara views as a terrorist group. YPG's fight against the Islamic State "is nothing but a huge lie," he added.

Referring to comments made by U.S. National Security Adviser John Bolton in Israel on Sunday, Erdogan said Turkey would not accept them, claiming they contradict a "clear agreement" he had with U.S. President Donald Trump.

The New York Times added some key context on Monday, writing that "Mr. Bolton is not a member of his inner circle. He does not have the same relationship with Mr. Trump that he had with Mr. Bush. Sometimes, with aides, the president refers to him as “Mike Bolton.”

"Elements of the U.S. administration are saying different things," he said.

Speaking to members of his AK Party in parliament, Erdogan also said Kurdistan Workers Party (PKK) militants, who operate mostly in Turkey, and Syrian-based YPG "are the same," adding the PKK "cannot be representatives of Kurds."

Turkey's preparations for a new military offensive against terror groups in Syria are "to a large extent" complete, Erdogan said. Ankara "cannot make any concessions. Those involved in a terror corridor (in Syria) will receive the necessary punishment."

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Open gallery view File photo: U.S. National Security Adviser John Bolton attends a meeting with President Donald Trump and senior military leadership at Al Asad Air Base, Iraq, December 26, 2018. Credit: Andrew Harnik/AP

Bolton met with his Turkish counterpart Ibrahim Kalin earlier on Tuesday, and a spokesman for the U.S. National Security Council said they had a productive discussion regarding the United States' decision to withdraw from Syria, adding the two sides had identified further issues for dialogue.

With tensions simmering over Trump's Syria strategy, President Erdogan hadn't met with Bolton.

Erdogan warned on Monday the U.S. withdrawal must be planned carefully and with the right partners, saying only Turkey had "the power and commitment to perform that task."

In an op-ed article for the New York Times, Erdogan said Turkey was committed to defeating ISIS and "other terrorist groups" in Syria.

Speaking to The Associated Press from northern Syria on Monday, a Syrian Kurdish official said the Kurds have not been informed of any change in the U.S. position and were in the dark about Bolton's latest comments.

"We have not been formally or directly notified, all what we heard were media statements," Badran Ciya Kurd said.

Kurdish officials have held conversations with Moscow and Syrian President Bashar Assad's government about protection, but Bolton called on them to "stand fast now."

Trump said last month he was bringing home the some U.S. 2,000 troops in Syria, saying they had succeeded in their mission to defeat Islamic State. His abrupt move sparked concern among officials in Washington and allies abroad and prompted Defence Secretary Jim Mattis to resign.

In late December, Trump said he spoke with Erdogan, who assured him that Turkey would "eradicate whatever is left of ISIS." The Turkish president "is a man who can do it plus, Turkey is right 'next door,'" Trump said.

A Turkish official later told Reuters that "Trump asked: 'If we withdraw our soldiers, can you clean up ISIS?'" He said Erdogan replied that Turkish forces were up to the task.

"Then you do it," Trump told him abruptly, according to the source. To his national security adviser John Bolton, also on the call, Trump said: "Start work for the withdrawal of U.S. troops from Syria."

Trump on Monday struck back at the perception that his intentions in Syria had changed. "No different from my original statements, we will be leaving at a proper pace while at the same time continuing to fight ISIS and doing all else that is prudent and necessary!....." he said in a tweet.

The YPG has been the key U.S. ally in its fight against Islamic State, support that has long caused tension between Washington and Ankara. Turkey views the YPG as an extension of the outlawed PKK, which has waged a three-decade insurgency in Turkey's mainly Kurdish southeast.

Speaking to reporters in Jerusalem ahead of a meeting with Prime Minister Benjamin Netanyahu, Bolton said that the U.S. military withdrawal from northeastern Syria is conditioned on defeating ISIS and on Turkey assuring the safety of Kurdish fighters. He added that there is no timetable for the pull-out of American forces, but insisted it's not an unlimited commitment.

The Associated Press contributed to this report.