Oil prices surged after the United Nations maritime agency canceled plans to evacuate stranded vessels around the Strait of Hormuz following an attack on a cargo ship in the waterway.
International benchmark Brent crude rose as much as 4 percent on Thursday after the International Maritime Organization (IMO) paused the evacuation amid escalating violence in the strait.
Brent futures for August delivery traded at $74.89 a barrel at 02:00 GMT, after dropping below $72.48 earlier, the close a day before the U.S. and Israel launched war against Iran.
After a sharp decline following the signing of a memorandum of understanding between the U.S. and Iran to end the war last week, Brent is now about 3 percent higher than pre-war levels.
Asian markets opened lower on Friday, with major indexes in Japan, South Korea, Hong Kong and Taiwan posting heavy losses.
Tokyo's Nikkei 225 and Seoul's Kospi both fell more than 3 percent in morning trade, while the Taiex dropped about 1 percent.
In Hong Kong, the Hang Seng index fell about 1 percent.
The latest attack in the Strait of Hormuz, which in peacetime carries about one-fifth of the world's crude oil and liquefied natural gas, dealt a heavy blow to hopes of restoring normal shipping operations after a recent recovery.
On Wednesday, 70 vessels passed through the waterway, more than double the day before and the highest since March 1, according to ship-tracking platforms MarineTraffic and Kpler.
The United Kingdom Maritime Trade Operations (UKMTO) said on Thursday that a cargo vessel reported being hit by an "unidentified object" on its starboard side while attempting to cross the strait near the coast of Oman.
Multiple media outlets, including The New York Times, CBS News and Reuters, citing unnamed U.S. officials, attributed the attack to Iran.
Iran's Persian Gulf Strait Management Authority, which claims the right to regulate maritime traffic in the strait, said after the attack that any ship attempting to use routes outside designated "frameworks" would not be guaranteed safe passage.
"Consequences arising from passing through unauthorized routes will be the responsibility of the owners, operators and captains," the authority said on X.
June Goh, senior oil analyst at Sparta in Singapore, said the attack was a reminder to the market of the fragility of peace in the strait amid a shaky ceasefire between the U.S. and Iran.
"There is an urgent need for tankers to enter and discharge the high inventory of crude oil from onshore storage tanks so normal production can resume," Goh told Al Jazeera.
"Therefore, security of the route is paramount to restoring lost supply."
