Oil refiners in Japan, the world's fourth-biggest importer of crude oil, are gathering information on supplies from Saudi Arabia following an attack on the kingdom's key crude oil facilities over the weekend, company officials said Tuesday.

The attack on state-owned producer Saudi Aramco's crude processing facilities at Abqaiq and Khurais cut output by 5.7 million barrels per day and threw into question its ability to maintain oil exports.

Saudi Aramco has not given a specific timeline for the resumption of full output. Saudi Arabia is the world's biggest oil exporter and has been the supplier of last resort for decades.

Officials from JXTG Holdings, Idemitsu Kosan Co. and Cosmo Energy Holdings Co. said they were collecting information but declined to comment further on Saudi Arabian oil or alternative supplies.

"We don't expect any major problem on our crude procurement," said a Fuji Oil spokesman, pointing to the company's capability to get alternative supplies.

The government will consider the coordinated release of oil reserves and other measures if needed to ensure sufficient supplies after the attack on Saudi oil facilities, industry minister Isshu Sugawara said earlier Tuesday.

Sugawara said in a statement Monday that Japan has oil reserves for about 230 days of domestic consumption.

He added that while he has not heard whether the attack will disturb Japan's procurement, "it is conceivable that it will take a long time to restore the situation. We need to make sure that people's lives and our economy won't be affected."

The Nikkei 225 stock average edged up to a four-month high as soaring oil prices triggered by the attack boosted oil and gas-related companies.

Oil prices ended nearly 15 percent higher Monday, with Brent logging its biggest jump in over 30 years amid record trading volumes.