Brent crude futures rose as much as 19.5% - their the biggest intraday jump since January 14, 1991

Oil prices soared on Monday, with Brent crude posting its biggest intraday percentage gain since the Gulf War in 1991, after an attack on Saudi Arabian oil facilities on Saturday shut about 5 per cent of global supply.

Brent crude futures, the international benchmark for crude oil, rose by as much as 19.5 per cent to $71.95 per barrel, the biggest intraday jump since January 14, 1991. The front-month contract was at $66.28 per barrel, up $6.06, or 10.1 per cent, from its previous close, by 0449 GMT (10:19 am in India).

US West Texas Intermediate (WTI) futures climbed by as much as 15.5 per cent to $63.34 a barrel, the biggest intra-day percentage gain since June 22, 1998. The front-month contract was at $59.77 a barrel, up $4.92, or 9 per cent, at the time.

Saudi Arabia is the world's biggest oil exporter and the attack on state-owned producer Saudi Aramco's crude processing facilities at Abqaiq and Khurais has cut output by 5.7 million barrels per day. The company has not given a timeline for the resumption of full output.

A source close to the matter told news agency Reuters the return to full oil capacity could take "weeks, not days".

Saudi Arabia's oil exports will continue as normal this week as the kingdom taps into stocks from its large storage facilities, an industry source briefed on the developments told Reuters on Sunday.

"We think the attacks would be a wake up call for investors, who have failed to price in risk within the price of crude. Although global supply will contract in the near term, the United States has the ability to supply this contraction," said Hue Frame, managing director at Frame Funds in Sydney.

"With developments over the weekend, market participants will add additional factors when working out the fair value of crude on top of the usual supply and demand factors."

US President Donald Trump said he approved the release of oil from the US Strategic Petroleum Reserve (SPR) if needed in a quantity to be determined due to the attack.

The attack on plants in the heartland of Saudi Arabia's oil industry, including the world's biggest petroleum-processing facility at Abqaiq, came from the direction of Iran, and cruise missiles may have been used, according to a senior US official. Initial reports indicated the attack came from Yemen.

Mr Trump also said the US was "locked and loaded" for a potential response to the attack on Saudi Arabia's oil facilities.

Risk premium

"A geopolitical risk premium will return to the oil price," said Alan Gelder, vice president for refining, chemicals and oil markets at Wood Mackenzie.

"This attack has material implications for the oil market, as a loss of 5 million barrels per day of supplies from Saudi Arabia cannot be met for long by existing inventories and the limited spare capacity of the other OPEC+ group members," he said.

Saudi Arabia is set to become a significant buyer of refined products after the attacks, consultancy Energy Aspects said in a note.

Saudi Aramco will likely buy significant quantities of gasoline, diesel and possibly fuel oil while cutting liquefied petroleum gas exports.

US gasoline futures rose as much 12.9 per cent, while US heating oil futures rose by as much as 10.8 per cent. China's Shanghai crude oil futures rose to its trading limit, gaining 8 per cent at the open.

Meanwhile, Saudi Aramco has told one Indian refinery there will be no immediate impact on oil supplies as it will deliver crude from other sources and has adequate inventory, a source with the refinery said.

Other Asian buyers such as Thailand have also said the attack would have no immediate impact on oil imports.