The UK Foreign, Commonwealth & Development Office advises against travel to Iran; the embassy continues to operate remotely.

"If you are a British citizen and are already in Iran, whether as a resident or a tourist, carefully consider your stay there and the risks associated with it.

Follow local and international media for the latest information.

Avoid areas located near security facilities or military sites.  Constantly review your departure plans.

British citizens wishing to leave Iran via Armenia do not need a visa to stay in Armenia for up to 180 days per year," the statement says.