Chinese bookings for tankers carrying crude oil from the Persian Gulf have risen in recent days, adding to signs that the biggest importer is sourcing more from the area amid shipping disruptions in the Red Sea.

So far this week, at least 10 Very Large Crude Carriers were provisionally booked from the Persian Gulf to China, according to fixtures compiled by Bloomberg. It’s unusual for that number of supertankers to be arranged in just three days. There were fewer bookings than that in the whole of last week.

Crude oil shipping routes have been roiled this year as Iran-backed Houthi rebels in Yemen target commercial vessels in the Red Sea, forcing many shippers to avoid the area and pushing up freight rates. 

That’s prompted buyers such as China to source more crude from places that are able to use routes avoiding trouble spots, including eastbound shipments from Persian Gulf producers such as Saudi Arabia.

Oil from the Persian Gulf to Asia is normally transported in VLCCs that carry about 2 million barrels, while tankers hauling cargoes from Kazakhstan or Russia are often moved in smaller vessels.

Tanker earnings on the benchmark Persian Gulf-to-China route were at $51,517 a day on Wednesday, about 40% higher than a week earlier, according to Baltic Exchange data.