The benchmark US oil contract increased more than 2.5 per cent when markets opened Wednesday, as Mideast tensions rose with new US attacks on Iran.

West Texas Intermediate crude, one of the two major global benchmarks, was up 2.63 percent at $72.29 per barrel. It rose 2.76 percent on Tuesday.

The rise came after US forces launched strikes on Iran after three commercial vessels were attacked in the Strait of Hormuz, according to the US military.

Iranian state media reported numerous explosions around the strait, including six on the island of Qeshm, seven in the city of Sirik and more in the major port city of Bandar Abbas.

Oil prices are still well below the peaks they shot up to as the war began in late February and Iran largely shut down the Strait of Hormuz.