Istanbul: A tweet sent by US Central Command insisting its Kurdish allies in the fight against IS in Syria are not linked to outlawed militants in Turkey whipped up a storm on Thursday, with Ankara asking if Washington had "lost its senses".
Relations between the United States and Turkey have become increasingly bitter in the last month, with Ankara expressing hope of a "new chapter" under President-elect Donald Trump.
Turkey argues the Kurdish fighters backed by Washington in the fight against Islamic State (IS) jihadists in Syria are a branch of the outlawed Kurdistan Workers Party (PKK), while Washington insists they are part of a legitimate multi-ethnic opposition group called the Syrian Democratic Forces (SDF).
"SDF confirms that it has no affiliation or ties to PKK," the US Central Command (CENTCOM) said on Twitter.
It posted a copy of a SDF statement saying it was made up of Arab, Turkic and Assyrian as well as Kurdish factions.
But analysts see the SDF as dominated by the Kurdish Peoples Protection Units (YPG), the armed wing of the Democratic Union Party (PYD).
Turkish President Recep Tayyip Erdogan calls the YPG as a "terror group" over links to the PKK, and has repeatedly blasted the US for working with the group on the ground in Syria.
"Is this a joke or @CENTCOM has lost its senses? Do you believe anyone will buy this? The US must stop trying to legitimise a terrorist group," Erdogan's spokesman Ibrahim Kalin tweeted.
Serdar Kilic, Turkey's ambassador to Washington, added: "@CENTCOM this account must be hacked by PKK".
The US backing of the YPG and criticism of the human rights climate in Turkey has angered Ankara in the final months of the administration of President Barack Obama.
"America's friends and allies are watching closely to gauge how America will reposition itself globally once President-elect Donald Trump is sworn in," Turkey's Foreign Minister Mevlut Cavusoglu said Thursday.
In a media report, he said that America's "continued insistence in Syria of working with a terrorist organisation" had placed the Turkey-US relationship under "severe strain".
Turkish officials have also expressed hope the Trump administration will hand over Erdogan's arch enemy Fethullah Gulen -- who he blames for the July 15 failed coup and who lives in self-imposed exile in the US.