Houthi attacks which have rerouted ships toward longer journeys around Southern Africa have sharply raised cargoes of oil at sea and hiked ship refuelling sales at Singapore to all-time highs, the International Energy Agency said on Thursday.

"In February alone, oil on water surged by 85 million barrels as repeated tanker attacks in the Red Sea diverted more cargoes around the Cape of Good Hope," the Paris-based energy watchdog said in a monthly report.

"At nearly 1.9 billion barrels as of end-February, oil on water hit its second highest level since the height of the Covid-19 pandemic."

The attacks in the Middle East contributed to the rise of longer journeys globally, as sanctions on Russian barrels had already been sending cargoes on new routes to reach more distant markets.

For Singapore - the world's top centre of maritime refuelling, or bunkering - the IEA raised its forecast for 2024 deliveries this year by 110,000 barrels per day (bpd), most of it fuel oil.

The rerouting of ships is also increasing bunkering at smaller southern African refuelling ports, the IEA added, such as Walvis Bay in Namibia, Richards Bay and Durban in South Africa and Port Louis in Mauritius.

"Efforts to make up time by sailing at increased speed act as an additional boost to fuel consumption," the IEA added.

(Reporting By Noah Browning; Editing by Elaine Hardcastle)