President Recep Tayyip Erdogan on Sunday rejected calls for Turkey to arm the main Kurdish party in Syria, describing the group as a terrorist organisation.
Erdogan said the Democratic Union Party (PYD) was the same as the outlawed Kurdistan Workers' Party (PKK), which has waged a 30-year insurgency for self-rule in southeastern Turkey.
The armed wing of the PYD, the Kurdish People's Protection Units (YPG), has been engaged in heavy fighting in recent weeks with the Islamic State group for control of the northern Syrian town of Kobane.
"There has been talk of arming the PYD to form a front here against the Islamic State. For us, the PYD is the same as the PKK, it's a terrorist organisation," Erdogan said aboard a plane returning from Afghanistan.
"It would be very, very wrong to expect us to openly say 'yes' to our NATO ally America to give this kind of support. To expect something like this from us is impossible," he was quoted as saying by the state-run Anatolia news agency.
French President Francois Hollande last week called on Turkey to open open its border to allow reinforcements to reach Kobane while the PYD itself called on Ankara to allow its territory to be used for transferring weapons.
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The United States said on Thursday it held direct talks for the first time with the PYD.
Ankara is reluctant to arm Kurds and intervene militarily against the jihadists, fearing the creation of an effective Kurdish fighting force on its border.
Turkey has long linked the PKK to the PYD, although the Syrian group rejects the claims.
Ankara also accuses the PYD of not working to oust Syrian President Bashar al-Assad, who Turkey has staunchly opposed since the conflict erupted in March 2011.
"They are complicit in the crimes committed by the Syrian regime," Prime Minister Ahmet Davutoglu said at a press conference in Ankara.
"We would have a different attitude towards the PYD and Kobane" if the PYD had kept its promises to work to topple Assad, he said.