Jet2 planes from the UK to Spain turned back in mid-air as the airline announced it was cancelling all flights to the country amid the coronavirus outbreak.
New infections have risen sharply in Spain and the government put 60,000 people in four towns on a mandatory lockdown on Friday.
Prime minister Pedro Sanchez said a two-week state of emergency will come into force as the death toll reached 120.
Jet2, which is based at nine UK airports and flies to destinations including Alicante, Malaga and Lanzarote, said it was cancelling all flights to mainland Spain, the Balearic Islands and the Canary Islands with immediate effect.
A spokeswoman for the airline confirmed on Saturday morning that flights had turned back.
A statement from Jet2 said: "In response to local measures introduced throughout Spain to prevent the spread of Covid-19, including the closure of bars, restaurants, shops, and activities including any water sports, we have taken the decision to cancel all flights to mainland Spain, the Balearic Islands and the Canary Islands with immediate effect.
"We know these local measures will have a significant impact on our customers' holidays, which is why we have taken this decision.
"We are contacting our customers who are currently in these destinations, and who are due to travel, to advise them of their options, so we urge customers not to call us.
"This is a fast-moving and complex situation and we are reviewing our programme as a matter of urgency, so that we can fly customers back to the UK.
"The health and safety of our customers is our number one priority, and we would like to thank our customers for their understanding."