A British nuclear-powered submarine, HMS Anson, which is equipped with Tomahawk cruise missiles, has reportedly traveled nearly 9,000 kilometers from its previous deployment off Australia to take up position in the Arabian Sea in the latest development of the war in Iran.

The United Kingdom government's defense ministry has declined to comment on the report, but if confirmed it would back up its decision to allow the United States to use British air bases to launch attacks on sites in Iran that are targeting the globally-vital Strait of Hormuz shipping lane.

That change of heart by the government was announced after it emerged that Iran had tried to fire missiles at the joint UK and US-maintained military base on the Chagos Islands, in the Indian Ocean.

The Wall Street Journal and broadcaster CNN reported that two missiles were fired at the island of Diego Garcia, but neither reached its target, with one being intercepted, and the other failing in flight.

British Foreign Secretary Yvette Cooper told the BBC that the government's position remained that it wanted a swift end of the conflict, and it did not want to be drawn into a regional war, but she said taking defensive action was supporting UK interests.

"As the prime minister has made clear we will provide defensive support against these reckless Iranian threats, but we have not been — and we continue not to be — involved in offensive action," she said. "We will not be drawn into a wider conflict because we think we need to see as swift as possible resolution in the UK national interest but also to support regional stability."

Israeli authorities have claimed that Iran now has the capability to target European cities with its missiles, but British government minister Steve Reed said there was no reason to think that this was likely or even feasible.

When asked why Israel had said this, he said "You would need to speak to the Israelis", while also reiterating Cooper's comments about keeping British nationals and interests safe through what he called "appropriate collective defensive action".

This comment came after the leaders of Britain, France, Germany, Italy, the Netherlands and Japan issued a joint statement signaling their "readiness to contribute to appropriate efforts to ensure safe passage through the (Hormuz) Strait" as part of efforts to try and bring global energy prices back under control, after the war sent fuel costs soaring.

As a consequence of that, US President Donald Trump has threatened — at 23:44 London time on Saturday — to "obliterate" power plants in Iran unless the Strait of Hormuz is reopened to all vessels within 48 hours.