Oil prices rose by around $1 on Tuesday as renewed fighting between the United States and Iran heightened fears of supply disruptions from the Middle East.
Brent crude futures gained $1.05, or 1.2 percent, to $91.54 a barrel at 0455 GMT. US West Texas Intermediate crude rose $1.27, or 1.5 percent, to $87.03.
The gains followed a strong session on Monday, when Brent settled 2.7 percent higher after briefly hitting its highest level since August 25. WTI closed 2.8 percent higher and touched its strongest level since August 21.
The latest rise came after US President Donald Trump threatened further strikes on Iran. The warning followed the first direct exchange of attacks between the two countries in a month on Sunday.
Markets are now watching closely for any impact on oil infrastructure and shipping in the Gulf, particularly around the Strait of Hormuz.
“These bring the potential for Iranian retaliation back into the equation,” said Tim Waterer, chief market analyst at KCM. He said this could increase the risk of damage to energy infrastructure and create further uncertainty for shipping through the waterway.
Shipping activity through the Strait remains well below normal levels. Kpler data showed only five visible commodity vessels crossed the waterway on Monday, compared with a 10-day average of about 14. None of the vessels were oil tankers.
Mediation efforts by Qatar and Oman to reopen the Strait have so far made little progress. The waterway carried about a fifth of global oil supplies before the conflict began in late February.
The risks to shipping remain high. The UK Maritime Trade Operations agency said on Tuesday that a tanker reported being struck by three projectiles while leaving the Strait. No casualties or environmental damage were reported.
ANZ analysts said oil flows through Hormuz were estimated at around 6 million barrels per day, still well below pre-conflict levels.
They also warned that global supply buffers were shrinking, with US inventories nearing minimum levels and China’s ability to maintain lower imports likely to face pressure as seasonal demand rises.
Read next: Supply fears lift oil prices despite weaker global demand