On Wednesday night, Sir Keir also met the Saudi Crown Prince Mohammed bin Salman, who agreed on the need for a lasting peace.
This evening, Cooper is expected to say that the war has affected “every country on every continent”, driving up food and petrol prices in the UK.
She will call for shipping in the Strait of Hormuz to be toll-free and unhindered after reports that vessels could be forced to make payments to Iran in exchange for safe passage.
Ministers accept the real decisions lie in the hands of the US and Israel – and the foreign secretary will call on them to include Lebanon in the ceasefire deal.
“There is considerable work to do and we support the negotiations,” Cooper will say, outlining that there must be no return to conflict.
She will emphasise that the Strait or Hormuz must reopen as the “deliberate blocking of this critical artery of the global economy” is affecting British people, despite being more than 3,000 miles away.
“This is an international shipping route, a transit route for the High Seas,” Cooper will add.
“No country can close these routes – it goes against the fundamental principles of the law of the sea.”
The foreign secretary will also visit the International Maritime Organization on Thursday in a show of support for the organisation’s efforts to help ships and seafarers currently trapped in the waterway.
“The full and unconditional re-opening of the Strait must be a central part not just of the current ceasefire but of the long term future for the region,” she will reiterate.
