Closing the strait to commercial shipping has been a longstanding threat from Iran. File Image / Pixabay

Commercial ships operating in the Middle East are reportedly being warned the Strait of Hormuz has been closed following strikes on Iran on Saturday, according to a British government agency monitoring maritime security in the region.

The US and Israel attacked a series of military facilities in Iran on Saturday, with Iran responding with strikes on US bases across the Middle East.

Iran may now be claiming to have closed the Strait of Hormuz to shipping traffic, the UK Maritime Trade Operations agency said in a social media post.

"UKMTO continues to monitor the maritime security situation amid significant military activity in the region, and has received multiple reports from Company Security Officers (CSOs) of vessels operating in the Arabian Gulf stating that VHF Channel 16 broadcasts have claimed that the Strait of Hormuz (SoH) has been closed," the agency said.

"These reports cannot be independently verified at this time.

"Mariners are advised that VHF broadcasts or statements indicating closure of the Strait of Hormuz are not legally binding and do not constitute a lawful restriction on navigation under international law."

The Strait of Hormuz is a key chokepoint for the global shipping industry, particularly for tanker traffic in the Middle East, and closing the strait to commercial shipping has been a longstanding threat from Iran on how it might respond to war. While Iran can quickly discourage commercial shipping from operating in the area by threatening attacks, there is significant doubt among experts over whether it could practically prevent all traffic through the area on a long-term basis in the face of US naval opposition to such a move.

A key element to watch in the coming hours and days will be whether Iranian forces choose to lay mines in the area to discourage ships.

Another consideration will be the fact that the majority of Iran's crude exports are currently sent to China and would be blocked by the closure of the strait.