US Vice President Joe Biden on Tuesday added Saudi Arabia to the list of Middle Eastern countries to which he "clarified" remarks he made last week suggesting they had supported Islamist militants in Syria.

He apologized to Turkey and the United Arab Emirates last weekend for having said U.S. allies in the region were partly to blame for the rise of the Islamic State group in Syria. He made the statements in a question-and-answer session with students at Harvard University.

"Vice President Biden spoke today with Saudi Arabia's Minister of Foreign Affairs, Prince Saud al-Faisal," Biden's office said in a statement.

"The vice president thanked the foreign minister for Saudi Arabia's strong support in the shared fight against ISIL and he clarified his recent remarks regarding the early stages of the conflict in Syria. The two agreed that the issue was closed."

ISIL (Islamic State of Iraq and the Levant) is the acronym used by the United States for Islamic State.

Biden had said U.S. allies in the region, many now participating in a coalition to fight Islamic State, had poured millions of dollars into Syrian groups fighting against President Bashar al-Assad, which strengthened the Islamist factions there.

White House spokesman Josh Earnest strongly defended Biden on Monday as a core member of Obama's foreign policy team.

"The vice president is somebody who has enough character to admit when he's made a mistake," said Earnest. – Reuters