Airlines are scrambling to cancel and divert flights to and from the Middle East following the US and Israel’s strikes on Iran.
British Airways and Virgin Atlantic are among the carriers grounding flights, with Dubai International and Al Maktoum International airports in Dubai suspending operations.
The UK Foreign Office is advising British citizens to avoid non-essential travel to Bahrain, Kuwait, Qatar, and the UAE, and those already in these countries are being told to shelter in place.
The situation is fluid, with many airlines offering rebooking options or full refunds for affected passengers.
This came after Iran launched retaliatory attacks on the Gulf states.
Long-haul travel is being affected more widely and Heathrow has urged travellers to check with their airlines.
One person has been killed and 11 others were injured at airports in Dubai and Abu Dhabi. Four of those injuries were among members of staff at Dubai International.
British Airways has cancelled services to Tel Aviv and Bahrain until Wednesday.
It said services between Heathrow and Abu Dhabi, Amman, Bahrain, Doha, Dubai or Tel Aviv could be affected for several days.
Virgin Atlantic said it was suspending services between Heathrow and Riyadh on Sunday, after earlier cancelling flights from Heathrow to Dubai on Saturday and Sunday.
It has warned that flights to India, Saudi Arabia and the Maldives may take longer due to them being rerouted around the affected region.
Virgin is among airlines across Europe, Asia and the Middle East that have had to cancel or reroute flights to avoid the closed or restricted airspace.
Airspace over Iran, Israel, Iraq, Qatar, Bahrain, Kuwait, Syria and the UAE remained closed on Sunday morning, while there is a partial closure in Saudi Arabia. Jordanian and Lebanese airspace remains open but there is limited flight activity.
