Crude oil futures surged more than 4% after two tankers were attacked in the Gulf of Oman, a key waterway used to transport energy supplies from the Middle East.
The Japanese owner of the Kokuka Courageous told CNN the 27,000-ton tanker had been attacked "by some sort of shell" off Fujairah, a port in the United Arab Emirates. The ship suffered damage to its starboard hull.
The ship's operator, Singapore-based BSM Ship Management, said in a statement that the Kokuka Courageous was about 14 nautical miles from the coast of Iran.
A second tanker, the Front Altair, was also attacked while sailing between the UAE and Iran, the Norwegian Maritime Agency said in a statement.