Rishi Sunak is due to hold a full cabinet call this evening which is thought to be about UK and US military strikes against Yemen’s Houthi rebels.
The meeting is due to start at 7.45pm tonight.
Attacks by Houthi fighters – both on Israel and on commercial ships in the Red Sea – have stoked fears of a wider conflict in the region already affected by the war in Gaza.
On Tuesday, a British warship shot down seven drones launched by the Iranian-backed Houthi fighters in an operation with US forces to repel the largest drone and missile attack to date.
The attack came despite a warning by the United States, the UK and other partners issued a week ago to the group to end the targeting of commercial shipping or “bear the responsibility of the consequences”.
Earlier today Defence Secretary Grant Shapps accused Iran of meddling and declared “enough is enough” – hinting that the UK could be ready to strike.
Holding a last-minute evening cabinet meeting is an unusual step.
Sky News’s deputy political editor Sam Coates said: “Downing Street haven’t formally briefed why this call is happening, but a cabinet meeting only happens at short notice when there’s a moment of national importance.”
Sir William Patey, a former ambassador to several countries in the Middle East, also told Sky News: “You don’t hold an emergency cabinet meeting unless you’re considering a military response.
“The Americans have clearly put some military options on the table and have invited us to participate.”
Sky News understands that Speaker of the House of Commons, Sir Lindsay Hoyle, has also been called to a briefing in Whitehall tonight.
Why are the Houthis attacking ships in the Red Sea
It comes as the US confirmed a 27th Houthi attack on international shipping since 19 November.
The attack happened at 2am Yemen time in the Gulf of Aden.
Sir William said that given the Houthis have ignored warnings to stop attacking shipping, continuing to intercept drones is not “in the long term very feasible”.
He said: “I’m sure that the Americans, Brits, and other members of the international coalition will be considering whether there are feasible targets that can be struck in Houthi-run territory of Yemen that are viable.”
However he said that an issue in the past has been finding viable targets, which he defines as bases where missiles are launched from or stored, for example.
The US in particular is under pressure to re-establish proper deterrents against the Houthi rebels.
Admiral John Kirby told reporters on Thursday he “wouldn’t telegraph anything”, but added: “We’re going to do what we have to do to counter and defeat these threats towards commercial shipping in the Red Sea.”
Concerns are growing about the global economic impact of the disruption to shipping through the vital Red Sea, with vessels choosing to divert, pushing up the cost of trade and potentially causing inflation to rise.
The Houthis, a group of Shia Islamists based in western Yemen, oppose US and Israeli influence in the Middle East – with its slogan containing the words “death to America”, “death to Israel” and a “curse upon the Jews”.