Turkish President Tayyip Erdoğan said U.S.-supplied weapons had been used against civilians by a Syrian Kurdish militia group that Ankara blames for a deadly suicide bombing, and said he would talk to President Barack Obama about it Friday.

U.S. support for the Syrian Kurdish PYD, which Washington considers a useful ally in the fight against the Islamic State group, has enraged Turkey and risks driving a wedge between the NATO allies. Turkey believes the terrorist organization, aka ISIS, is linked to Kurdish militants waging an insurgency on its own soil.

Erdoğan and the Turkish government have said the PYD's armed wing, the YPG, is responsible for a suicide car bomb attack in the administrative heart of the capital, Ankara, Wednesday that killed 28 people, most of them soldiers.

He said he was saddened by the West's refusal to call the PYD and YPG terrorists and would explain to Obama by phone how weapons provided by the United States had aided them.

"I will tell him, 'Look at how and where those weapons you provided were fired,'" Erdoğan told reporters in Istanbul.

"Months ago in my meeting with him I told him the U.S. was supplying weapons. Three plane loads arrived, half of them ended up in the hands of Daesh [ISIS], and half of them in the hands of the PYD," he said.

"Against whom were these weapons used? They were used against civilians there and caused their deaths."

Erdoğan appeared to be referring to a U.S. airdrop of 28 bundles of military supplies in late 2014 meant for Iraqi Kurdish fighters near the Syrian city of Kobani. Pentagon officials said at the time one had fallen into the hands of ISIS. The Pentagon later said it had targeted the missing bundle in an airstrike and destroyed it.

The United States has said it does not consider the YPG a terrorist group. A spokesman for the State Department said Thursday that Washington was not in a position to confirm or deny Turkey's charge that the YPG was behind the Ankara bombing.

The spokesman also called on Turkey to stop its recent shelling of the YPG. The YPG's political arm has denied the group was behind the Ankara attack and said Turkey was using it to justify an escalation in fighting in northern Syria.

'Conflicting and Confused'

Turkish Foreign Minister Mevlut Cavusoglu earlier accused the United States of making conflicting statements about the Syrian Kurdish militia.

He said U.S. Secretary of State John Kerry had told him the Kurdish insurgents could not be trusted, in what Cavusoglu said was a departure from Washington's official position.

"My friend Kerry said the YPG cannot be trusted," Cavusoglu said at a news conference during a visit to Tbilisi.

"When you look at some statements coming from America, conflicting and confused statements are still coming. ... We were glad to hear from John Kerry yesterday that his views on the YPG have partly changed."

Prime Minister Ahmet Davutoglu said Thursday the Ankara attack, in which a car laden with explosives was detonated next to military buses as they waited at traffic lights, was carried out by a YPG member from the Hasakah region of northern Syria working with Kurdish militants inside Turkey.

Erdoğan said the bomber may have had two accomplices.

Within hours of the Ankara attack, Turkish warplanes bombed bases in northern Iraq of the Kurdistan Workers Party (PKK), which has waged a three-decade insurgency against Turkey and which Davutoglu accused of collaborating in the car bombing.

Violence between Turkish security forces and the PKK has been at its worst since the 1990s after a 2 1/2 year ceasefire collapsed last July.

Two soldiers and a police officer were killed Friday in a PKK attack in the Sur district of the southeastern city of Diyarbakir, parts of which have been under round-the-clock curfew since December, the armed forces said.

Three other soldiers were killed when a building collapsed in the same district. The authorities also caught two people in a car loaded with 500 kg of explosives Thursday evening in the Dicle district of Diyarbakir, security sources said.