In this image made from a video broadcast on the Saudi-owned Al-Arabiya satellite news channel on Saturday, Sept. 14, 2019, a man walks through a parking lot as the smoke from a fire at the Abqaiq oil processing facility can be seen behind him in Buqyaq, Saudi Arabia. Drones launched by Yemen’s Houthi rebels attacked the world’s largest oil processing facility in Saudi Arabia and another major oilfield Saturday, sparking huge fires at a vulnerable chokepoint for global energy supplies. (Al-Arabiya via AP)

DUBAI, United Arab Emirates (AP) — On Sunday morning, Iran denied it was involved in Yemen rebel drone attacks the previous day targeting the world’s biggest oil processing facility and an oil field in Saudi Arabia, just hours after America’s top diplomat alleged that Tehran was behind the “unprecedented attack on the world’s energy supply.”

The attacks Saturday claimed by Yemen’s Houthi rebels resulted in “the temporary suspension of production operations” at the Abqaiq processing facility and the Khurais oil field, Riyadh said.

That led to the interruption of an estimated 5.7 million barrels in crude supplies, authorities said while pledging the kingdom’s stockpiles would make up the difference.

While markets remain closed Sunday, the attack could shock world energy prices. They also increased overall tensions in the region amid an escalating crisis between the U.S. and Iran over Tehran’s unraveling nuclear deal with world powers.

Late Saturday, U.S. Secretary of State Mike Pompeo directly blamed Iran for the attack on Twitter, without offering evidence to support his claim. The U.S., Western nations, their Gulf Arab allies and U.N. experts say Iran supplies the Houthis with weapons and drones — a charge that Tehran denies.

Iranian Foreign Ministry spokesman Abbas Mousavi dismissed Pompeo’s remarks as “blind and futile comments.”

“The Americans adopted the ‘maximum pressure’ policy against Iran, which, due to its failure, is leaning towards ‘maximum lies’,” Mousavi said in a statement.

First word of Saturday’s assault came in online videos of giant fires at the Abqaiq facility, some 330 kilometers (205 miles) northeast of the Saudi capital, Riyadh.

Machine-gun fire could be heard in several clips alongside the day’s first Muslim call to prayers, suggesting security forces tried to bring down the drones just before dawn. In daylight, Saudi state television aired a segment with its local correspondent near a police checkpoint, a thick plume of smoke visible behind him.

President Donald Trump called Saudi Arabia’s Crown Prince Mohammed bin Salman to offer his support for the kingdom’s defense, the White House said. The crown prince assured Trump that Saudi Arabia is “willing and able to confront and deal with this terrorist aggression,” according to a news release from the Saudi Embassy in Washington.

Saudi Aramco describes its Abqaiq oil processing facility in Buqyaq as “the largest crude oil stabilization plant in the world.”

The Khurais oil field is believed to produce over 1 million barrels of crude oil a day. It has estimated reserves of over 20 billion barrels of oil, according to Aramco.

There was no immediate impact on global oil prices as markets were closed for the weekend. Benchmark Brent crude had been trading at just above $60 a barrel.

Associated Press writer Amir Vahdat in Tehran, Iran, contributed to this report.