Iran denied on Sunday it was involved in Yemen rebel drone attacks the previous day that hit the world's biggest oil processing facility and an oilfield in Saudi Arabia, just hours after the United States's top diplomat alleged 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 oilfield, 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. The amount Saudi Arabia is cutting back is equivalent to over five per cent of the world's daily production.

Stéphane Dujarric, spokesperson for the UN Secretary-General, released a statement on Sunday in response to the attacks. He implored all parties to use "maximum restraint" in the conflict, and also to "comply at all times with International Humanitarian Law."

Oil prices surged more than 15 per cent at the open on Sunday, while traders and analysts said crude may spike to as high as $100 US a barrel if Riyadh fails to quickly bring back supply.

Late Saturday, U.S. Secretary of State Mike Pompeo took to Twitter to directly blame Iran for the attack, without offering evidence to support his claim.

"Amid all the calls for de-escalation, Iran has now launched an unprecedented attack on the world's energy supply," Pompeo wrote. "There is no evidence the attacks came from Yemen."

Later on Sunday, senior U.S. officials again said the American government believes there is no doubt Iran was responsible, saying satellite imagery and other intelligence show the strike was inconsistent with one launched from Yemen, where Iranian-backed Houthi rebels had claimed responsibility.

The U.S. government produced satellite photos showing what officials said were at least 19 points of impact at two Saudi energy facilities, including damage at the heart of the kingdom's crucial oil processing plant at Abqaiq. Officials said the photos show impacts consistent with the attack coming from the direction of Iran or Iraq, rather than from Yemen to the south.

A satellite image provided by NASA Worldview shows fires following the attacks in eastern Saudi Arabia. (The Associated Press)

Abbas Mousavi, Iranian Foreign Ministry spokesperson, on Sunday 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 toward 'maximum lies,'" Mousavi said in a statement.

Separately, Iraqi Prime Minister Adel Abdul-Mahdi's office issued a statement on Sunday denying the drone attack came from there.

The oil processing facility targeted by the attack is some 330 kilometres northeast of the Saudi capital of Riyadh. (CBC) Iraq "abides by its constitutions that prevents the use of its lands to launch aggressions against neighbouring countries," the statement said.

On Sunday, The White House did not rule out a potential meeting between President Donald Trump and the Iranian President Hassan Rouhani. White House adviser Kellyanne Conway said the attacks "did not help" prospects for a meeting between the two leaders during the United Nations General Assembly this month, but she left open the possibility it could happen.

"I'll allow the president [Trump] to announce a meeting or a non-meeting," Conway told Fox News Sunday.

The Trump administration's sanctions and "maximum pressure" campaign — a tough policy intended to force Tehran to negotiate a broader deal that further curbs its nuclear and ballistic missile program — will continue whether or not the two leaders meet, she added.

However, Conway said "You're not helping your case much," by attacking Saudi Arabia, civilian areas and critical infrastructure that affects global energy markets.

Iran has said it is unwilling to meet with Trump while crushing sanctions are in place over its nuclear program.

Conway also said the U.S. Energy Department is prepared to tap into the Strategic Petroleum Reserve if needed to stabilize the global energy supply.

Fires visible from space

First word of Saturday's assault came in online videos of giant fires at the Abqaiq facility, some 330 kilometres northeast of the Saudi capital of 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.

Later, rising smoke from the fires at the sites could be seen by satellites in space.

U.S. President Donald Trump called Saudi Arabia's Crown Prince Mohammed bin Salman to offer his support for the kingdom's defence, 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."

A screen grab from AFP in Saudi Arabia shows smoke billowing from the oil facility. (AFP/Getty Images) The facility processes sour crude oil into sweet crude, then transports it onto transshipment points on the Persian Gulf and the Red Sea or to refineries for local production. Estimates suggest it can process up to seven million barrels of crude oil a day. By comparison, Saudi Arabia produced 9.65 million barrels of crude oil a day in July.

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