US investigators believe Iran or groups it supports used explosives to damage four ships off the United Arab Emirates on Sunday, media reports say.
Military experts were reportedly sent to investigate the incident and found a large hole in each of the tankers.
No evidence has emerged to show that Iran was involved. The affected countries are yet to assign blame.
The incident has increased tensions between Iran, which borders the nearby Strait of Hormuz, and the US.
About a fifth of oil that is consumed globally passes through the strait. Last month, Iran threatened to close it if it was prevented from using the waterway.
This followed a US decision to end exemptions from sanctions for major importers of Iranian oil…