The Pentagon has notified US lawmakers of plans to bolster US defenses in and around the Strait of Hormuz to be prepared for a military response against Iran, a report said Friday.

New mine-detection and clearing equipment as well as improved surveillance capabilities are part of the planned build-up, said the Wall Street Journal, citing defense officials briefed on the requests.

The Pentagon also wants to modify ship weapons systems to best deal with Iranian attack boats in the Strait, said the report.

The moves highlight efforts to boost US military capabilities amid heightened tension with Iran and rising speculation of a strike from Israel over Iran's nuclear program.

The United States, France, Britain and Germany accuse Iran of seeking to build a nuclear bomb, but Tehran says its nuclear drive is peaceful.

In January the US aircraft carrier USS Abraham Lincoln passed through the Strait of Hormuz after Tehran threatened to close the strategic shipping route.

Iran's military and political leaders had earlier warned they could close the strait -- a key transit route for global oil supplies -- if increased Western sanctions over Tehran's suspect nuclear program halt Iranian oil exports.

Further ratcheting up pressure on the program, the UN atomic agency on Friday said in a new report that Tehran had substantially boosted uranium enrichment.

International Atomic Energy Agency said it "continues to have serious concerns regarding possible military dimensions" to Iran's nuclear program.