The United States has developed a plan under which an international military coalition would safeguard strategic waters off both Iran and Yemen, where Washington blames Iran and Iran-aligned fighters for attacks.

Chairman of the Joint Chiefs of Staff Marine General Joseph Dunford said that over the next couple of weeks the US will identify which nations might support the initiative.

Under the plan, the United States would provide command ships and lead surveillance efforts for the military coalition.

Allies would patrol waters near those US command ships and escort commercial vessels with their nation's flags.

Iran has long threatened to close the Strait of Hormuz, through which almost a fifth of the world's oil passes, if it was unable to export its oil, something US President Donald Trump's administration has sought as a way to pressure Tehran to renegotiate a deal on its nuclear programme.

General Dunford said: "We're engaging now with a number of countries to see if we can put together a coalition that would ensure freedom of navigation both in the Strait of Hormuz and the Bab al-Mandab."

"And so I think probably over the next couple of weeks we'll identify which nations have the political will to support that initiative and then we'll work directly with the militaries to identify the specific capabilities that'll support that," he said.

Last month, US Secretary of State Mike Pompeo blamed Iran for attacks on two oil tankers travelling in the Strait of Hormuz.