Mr. Biden had angered the two countries by accusing them of jumpstarting the terror group, the Islamic State, when they gave aid to rebels fighting Syrian President Bashar Assad.
"They poured hundreds of millions of dollars and thousands of tons of weapons into anyone who would fight against Assad," Mr. Biden said, during remarks to the John F. Kennedy School of Government at Harvard University. "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. We could not convince our colleagues to stop supplying them."
And specifically on Turkey, Mr. Biden said that "President [Recept Tayyip] Ergodan told me, he's an old friend, said, 'You were right. We let too many people [including foreign fighters] through.' Now they are trying to seal their border."
But Mr. Ergodan's denied making that statement.
On Sunday, the UAE said Mr. Biden said he was sorry during his talk with the Crown Prince, CNN reported. Mr. Biden's office, meanwhile, confirmed he "clarified that his recent remarks regarding the early stages of the conflict in Syria were not meant to imply that the UAE had facilitated or supported ISIL, al Qaeda or other extremist groups in Syria," CNN said. But the statements didn't use the word apology.
And to Turkey, Mr. Biden's spokeswoman Kendra Barkoff 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."
Neither country immediately commented on Mr. Biden's apologies.