Saudi Arabia will be forced to cut its oil production further and Asian buyers will have to wait an extra month for deliveries if Houthi rebels succeed in closing the Bab al-Mandab Strait, one of the last remaining routes carrying Gulf crude to global markets.

Bab al-Mandab, which connects the Red Sea with the Gulf of Aden and the Indian Ocean, has become critical to Saudi Arabia’s oil trade to Asia since the Iran war began in February. After Tehran closed the Strait of Hormuz, the kingdom has increasingly used its East‑West pipeline to move crude across the kingdom to Yanbu on the Red Sea, where it ships about 2.5mn barrels a day south through Bab al-Mandab to China, Japan and South Korea.

Tankers began reversing course after the Houthis declared a maritime embargo on Saudi shipping, halving the number of vessels that crossed the strait on Tuesday. RBC analyst Helima Croft warned of “extreme pressure” and said a broader war could push oil above its 2008 record of about $146 a barrel.

If the Houthi embargo holds, Saudi oil production will have to fall below 6mn b/d, roughly 1mn barrels below its March and April levels, and half of its actual capacity. Rerouting cargoes north through the Suez Canal would add about four weeks to the journey and raise fuel costs by more than $1.6mn per supertanker.