US and Iranian forces fired at vessels in waters around Iran on Saturday (Sep 5), including three Iranian oil carriers struck by the Americans and three tankers that Iran said it targeted while on unauthorised routes in the Strait of Hormuz.

US Central Command said it struck the three Iranian vessels, including one off the coast of Kharg Island, near Iran's oil export hub, after Iran's Islamic Revolutionary Guard Corps (IRGC) launched ballistic missiles at two US Navy ships.

“Let the message to the IRGC be clear: If you shoot at two of our ships, we will impose an even higher economic cost - taking out three of yours," said Admiral Brad Cooper, head of US Central Command, which oversees the US military in the Middle East.

The IRGC responded by threatening intensified strikes against US military vessels in the region, and said later it targeted the three tankers as well as three US-linked vessels in other areas.

"Do not be deceived by the 'terrorist' US military and refrain from any suspicious movement aimed at passing through unauthorised waterways," the IRGC Navy said in a statement carried on Iranian state TV. "Otherwise, you will be targeted."

Tasnim, the semi-official Iranian news agency, had reported that four US missiles hit a tanker in the area of Kharg's anchorage. Tasnim quoted local sources as saying there were no casualties and the tanker's crew was being evacuated.

No American personnel were harmed, Central Command said.

The exchange of attacks followed an escalation in the past week that threatens to deepen a conflict that has continued since the US and Israel launched strikes on Iran in February, disrupting global energy supplies and drawing opposition from a majority of Americans before congressional elections in November.