The number of tankers diverting on longer voyages around the Cape of Good Hope has increased to 100 from last week, according to a report from Oil Brokerage.

That’s a jump of about 45% from the firm’s count of 69 on Jan. 24. The vessels are carrying about 56 million barrels of crude and petroleum products, according to the report. 

Shipments of clean petroleum products — such as diesel-type fuel — via the Bab el-Mandeb Strait at the southern end of the Red Sea fell to 625,000 barrels-a-day last week, versus a “usual” two million, the report added.

Many vessels are avoiding the Red Sea route because of attacks by Houthi militants on merchant shipping, instead sailing around South Africa’s Cape of Good Hope.