ANKARA, Turkey -- U.S. Vice-President Joe Biden apologized Saturday to Turkish President Recep Tayyip Erdogan, who was angry over comments in which Biden said Erdogan had admitted that Turkey had made mistakes by allowing foreign fighters to cross into Syria.
Erdogan denied ever saying that and told reporters in Istanbul before Biden's apology that he "will be history for me if he has indeed used such expressions."
Biden spoke with Erdogan by phone on Saturday, the White House said.
"The vice-president apologized for any implication that Turkey or other allies and partners in the region had intentionally supplied or facilitated the growth of ISIL or other violent extremists in Syria," the White House said, referring to an acronym for the Islamic State group.
The spat comes as Turkey, a NATO ally, is expected to define the role it will play in the U.S.-led coalition against the Islamic state militants who have captured a swath of Iraq and Syria, in some cases right up to the Turkish border.
Responding to questions following his speech at the Harvard Kennedy School on Thursday, Biden described Erdogan as "an old friend." Biden added: "He (Erdogan) said: 'You were right. We let too many people through.' Now they're trying to seal their border."
Erdogan said: "I have never said to him that we had made a mistake, never. If he did say this at Harvard then he has to apologize to us."
"Foreign fighters have never entered Syria from our country. They may come to our country as tourists and cross into Syria, but no one can say that they cross in with their arms," Erdogan said.
He said Turkey had prevented 6,000 suspected jihadis from entering the country and deported another 1,000.
This week Turkey's parliament approved a motion giving the government powers for military operations across the border in Syria and Iraq and for foreign troops to use Turkey's territory.
On Friday, the two men also held a telephone discussion of ways their two countries "can work together to degrade and destroy (the Islamic State group) and restore security and stability to the region," according to the White House.
At Harvard, Biden said that "our biggest problem is our allies" in responding to the civil war in Syria.
"The Turks, who are great friends -- I have a great relationship with Erdogan, whom I spend a lot of time with -- the Saudis, the Emiratis, etc. What were they doing? They were so determined to take down (Syrian President Bashar) Assad and essentially have a proxy Sunni-Shia war," Biden said.
"What did they do? They poured hundreds of millions of dollars and thousands of tons of weapons into anyone who would fight against Assad -- except that the people who were being supplied were al-Nusra and al Qaeda and the extremist elements of jihadis coming from other parts of the world."