TOKYO  - Japan's biggest refiner, JXTG Holdings, is gathering information on Saudi Arabian oil supplies after a weekend attack on facilities in the kingdom, a company spokesman told Reuters by email on Tuesday.

The attack on 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. The company has not given a specific timeline for the resumption of full output. 

Monday was a public holiday in Japan, the world's fourth-biggest importer of crude oil. The JXTG spokesman declined to comment further on Saudi Arabian oil supplies.

(Reporting by Aaron Sheldrick; editing by Darren Schuettler) ((aaron.sheldrick@thomsonreuters.com; 81-3-6441-1320;))