The soldiers were killed on Saturday in a strike on a tank which was part of Turkey's operation against Kurdish militia in Syria, the biggest single Turkish loss of the campaign so far.

Turkey on January 20 launched operation "Olive Branch" in the northern Syrian region of Afrin, fighting Syrian Kurdish People's Protection Units (YPG) militia which Ankara sees as a terror group.

But the YPG is an ally of the United States in the fight against jihadists and Washington has openly backed and also armed the group, to Ankara's fury.

Several pro-government newspapers, including the Yeni Safak, Yeni Akit and Star dailies, on Sunday accused the US of supplying the anti-tank missile used in the attack, in what could mark a major escalation.

"We have information but it would not be right to make an announcement before a final conclusion is reached," Erdogan told journalists in Istanbul before heading on a trip to Rome and the Vatican.

"I spoke to our chief of staff (General Hulusi Akar) half an hour ago and we have some information but it would be wrong to say something before the conclusion is made."

"We have assessments... and whoever it is (who gave the weapon) they are walking together with the terrorists. Once it is made clear then we will share this with the whole world," he added.

Erdogan vowed that despite the losses, Turkey would press ahead with the operation "with determination".

He said that 935 "terrorists have been neutralised" so far in the operation. It was not immediately possible to verify this figure.

Top Turkish officials including Erdogan have refused to give any timescale for the operation, vowing it would continue as long as needed to defeat the YPG around Afrin.