A surge in freight rates is prompting crude buyers in Asia to shift more purchases to Middle Eastern oil, aiding spot market prices.

The jump in shipping costs, driven by a flurry of vessel bookings, has made long-haul crude such as US cargoes too expensive for Asian consumers, traders said. That’s caused buyers to grab spot barrels from the Persian Gulf, driving up cargo premiums and helping to support the market.

Oil has fluctuated since the start of the year as traders gauge the outlook for demand, as well as a slew of tensions in the Middle East. A decision by Saudi Arabia to steeply cut official oil prices to Asia highlighted underlying softness, but now the jump in freight costs is reverberating through the market.

“The pop in freight will now favor Middle Eastern grades,” Anastasia Zania and Christopher Haines, analysts at Energy Aspects Ltd., said in a note. “The stronger rise in US Gulf Coast freight has already driven Japanese and Indian refiners to pick up Murban, possibly at the expense of WTI,” they said, referring to a grade from Abu Dhabi and the US benchmark, West Texas Intermediate.

The premium of Murban futures increased further after soaring above $1 a barrel against the Dubai benchmark on Tuesday, the highest since late November, according to traders and PVM Oil Associates Ltd. data. Oman crude futures also jumped to the highest in more than a month.

Freight rates have been boosted in the past week by a flurry of supertanker booking activity for long-haul voyages by Sinokor Merchant Marine Co., which tightened vessel availability. Rates for the US Gulf Coast-to-China route surged to $9.86 million on Tuesday, up almost $2 million from a week earlier, Baltic Exchange data show.

Additional support for shipping costs has come from attacks on vessels in the Red Sea. Houthi rebels in Yemen carried out one of their largest missile and drone attacks to date on commercial shipping lanes in the Red Sea late Tuesday, highlighting sustained tensions in the area. 

“Even though we do not expect similar increases over the course of the week, freight rates should remain elevated ahead of the long weekend in the US on the back of tighter availability, strong sentiment across the board and weather-related disruptions for ship-to-ship operations,” EA analysts said. Jan. 15 is a Federal US holiday.