Prime Minister Sir Keir Starmer is chairing a Cobra meeting about the US and Israeli air strikes on Iran.
Explosions have been heard across five Iranian cities including the capital, Tehran, on Saturday, after negotiations to limit Iran's nuclear programme ended without an agreement this week.
The UK did not participate in the strikes. A government spokesperson said it would protect British interests in the region, adding: "We do not want to see further escalation into a wider regional conflict."
A Cobra meeting is an emergency committee, where ministers and officials meet to co-ordinate the government's response to an emerging situation.
Downing Street confirmed the Cobra meeting was under way on Saturday morning.
