The Pentagon has notified Congress of plans to deploy new mine-detection and clearing equipment in the waterway, through which a fifth of the world's oil is transported.

The U.S. military are also looking to modify weapons systems on ships and shore-launched cruise missiles, the journal said citing unnamed defense officials.

Surveillance in and around the strait will also be increased.

Iran has threatened to close the Strait of Hormuz in response to mounting international pressure over its disputed uranium enrichment program.

Western powers suspect Iran is seeking to create a nuclear bomb and have tightened sanctions. Tehran insists its nuclear intentions are purely peaceful.

The International Atomic Energy Agency (IAEA), the UN's nuclear watchdog, said in a confidential report on Friday Iran had ramped up production of higher-grade enriched uranium over the past months.

The IAEA also expressed concerns over "possible military dimensions to Iran’s nuclear program."

IAEA inspectors were barred from a key Iranian military site earlier this week.

Iran staged military exercises earlier this week in the south which it said was to train protection of its nuclear facilities.

There has been increasing speculation in recent weeks that Israel may carry out a military strike on Iran's nuclear sites. The United States has also refused to rule out force.

Mohammad Hejazi, deputy head of Iran's armed forces, said on Tuesday Iran would take pre-emptive action if it needed to protect its national interests.