The Turkish president rejected the proposal of his American counterpart in the letter and threw it in the trash, according to unnamed sources.

"President Recep Erdogan received the letter, thoroughly rejected it and threw it in the trash," the BBC quoted the Turkish presidential government as saying.

London-based Middle East Eye news agency citing anonymity from Turkish officials gave similar information. Some Turkish journalists also claimed the letter had been treated that way.

The news is causing a stir in both the United States and Turkey. Washington and Ankara have not yet commented.

Trump on October 9 sent a letter to Erdogan, threatening to impose economic sanctions if Turkey's military operation kills thousands of civilians in northern Syria and calls for a deal with the Kurds.

"World history will look at you positively if you do this properly and humane. But it will consider you forever evil if good things don't happen. Don't be a stubborn person. Don't be a fool, "wrote the US President.

The letter was sent the same day Erdgogan launched a military campaign against the Kurds in Syria, which Ankara considers terrorists. Turkey's goal is to push the Kurdish forces off the border, opening a safety buffer of about 32 km in northern Syria.

Trump's letter to Erdogan was published by the White House as an explanation in the context of the US president being considered a "green light" for Turkey to conduct military operations in Syria. Many US lawmakers sharply criticized the decision to withdraw 1,000 troops from Syria before Ankara attacked the Kurds.