Singapore: At least four Asian refiners bought U.S. ​crude this week, as ​the Strait of Hormuz remained effectively closed and refiners ​sought alternative supplies for delivery later this year, traders said.Shipping traffic at the Strait of Hormuz fell below the average for this month towards the ‌end of ⁠the week ⁠due to competing U.S. and Iran claims over control of the waterway.With no ​immediate prospect of a free flow of shipping through the strait, strong refining ​margins amid tight fuel supplies have encouraged refiners to secure crude inventories for the coming months from beyond the Gulf.South Korea's GS ​Caltex bought two million barrels of ⁠Mars crude from ‌Shell for November arrival. The crude was ​priced at ​a premium around $13-14 per barrel above the October Dubai benchmark, ⁠traders said.Japan's third-largest oil refiner, Cosmo Energy Holdings , ​bought Mars crude from Trafigura, while Eneos Corp, Japan's ​biggest refiner, purchased 2 million barrels of West Texas Intermediate (WTI) crude from Trafigura for November delivery with a premium over $10 per barrel above the October WTI price.Taiwan's state-owned CPC Corp bought 2 million barrels of WTI via a tender at a premium of ‌around $8 to $9 a barrel to Dated Brent. CPC also purchased crude from West Africa via the tender, the ​people said.The ​companies do not ⁠typically comment on commercial deals.Before the Iran war, Asia sourced more than half of its crude supply from the Middle East. The region ​imported 2.35 million barrels per day crude from the U.S. in July, a record high, according to data by ship tracking firm Kpler.This week, India's state-run refiners Hindustan Petroleum Corp and Mangalore Refinery and Petrochemicals Ltd also issued tenders seeking for crude.