Britons confined to a hotel in Tenerife over coronavirus will not be flown home until next month, unless they have tested negative, airline Jet2 has said.
It is understood travellers booked with Jet2 received messages saying it would not fly them to the UK until 10 March.
It comes after three more people were diagnosed with the virus in the UK on Thursday, including Northern Ireland's first confirmed case.
That patient had travelled from northern Italy via Dublin.
Northern Ireland's chief medical officer said "robust infection control measures" were in place.
On Thursday, health officials confirmed two new cases of the virus in England, who contracted the virus while they were in northern Italy and Tenerife.
It means 16 people have tested positive in the UK since the virus outbreak began in China in December.
Experts have warned of school closures and the cancellation of major sporting events, concerts and festivals in the UK in a bid to stop the spread of the virus, which causes Covid-19.
England's chief medical officer, Prof Chris Whitty, said transmission of the virus between people in the UK was "just a matter of time".
He said if the outbreak intensifies, it may be necessary to close schools and stop mass gatherings of people for "quite a long period of time, probably more than two months".
The World Health Organization also warned that the outbreak had reached a "decisive point" and had "pandemic potential".
Globally, more than 80,000 people have been infected. About 2,800 have died - the majority in China's Hubei province.
Former health secretary Jeremy Hunt told BBC Radio 4's Today programme: "If I was going to choose a country to be in when there is a pandemic I would choose the UK."
He added that the timeline of the virus was "at a moment of enormous significance".
Italy has seen at least 650 cases of coronavirus and 15 deaths, according to local authorities.
Meanwhile, British cyclists Chris Froome and Adam Yates are being tested for the virus after two Italian "staff members" tested positive during a race in the United Arab Emirates (UAE), which has since been called off.
"It's a shame that the UAE Tour has been cancelled but public health must come first," Froome said in a tweet.
What's happening in Tenerife?
Some 168 Britons are among 700 guests who remain in the Costa Adeje Palace in Tenerife after at least four guests, including an Italian doctor, were diagnosed with coronavirus.
On Thursday, the Canary Islands minister of health said a group of 130 low-risk guests - including around 50 British nationals - would be able to leave because they arrived on Monday and did not come into contact with the four Italians who tested positive.
However, airline Jet2 has said it will not fly home any passengers who have been staying at the hotel until they have completed two weeks in quarantine, or tested negative for the illness.
Lara Pennington, who is quarantined in the hotel with her family, told BBC Breakfast she was concerned that other Britons there were not taking isolation seriously enough.
Ms Pennington said she had sought a guarantee for her family's safety "given we have remained in isolation and there will be other passengers on the plane who have not only gone into the hotel grounds but have not been following the protocols".
"I think it would be unfair to me and my family and [would] put us at risk at that point," she said.
In a statement, Jet2 said: "We will not fly any customer who has stayed at the H10 Costa Adeje Palace during the quarantine, until this incubation period has passed or unless they have been explicitly tested for Covid-19 by a recognised authority and are confirmed as clear of the virus."
The Foreign Office said it was trying to clarify the situation with the Spanish authorities and was supporting all 168 British tourists at the hotel.
Prof Yvonne Doyle, medical director at Public Health England, previously said a health protection specialist had been sent from the UK to Tenerife to work with the Spanish authorities.
What should I do to minimise the risk?
The new cases in the UK come as the government prepares a public information campaign focusing on hygiene and how to prevent the spread of infection.
The current advice is to cover your mouth and nose with a tissue or sleeve when you cough or sneeze, throw away tissues immediately after use and wash your hands frequently.
It is also advised to avoid touching your eyes, nose or mouth with unclean hands and avoid close contact with people who are unwell.
What is the travel advice?
The Foreign and Commonwealth Office (FCO) is warning against all but essential travel to 11 quarantined towns in Italy, two cities in South Korea and mainland China.
The Department of Health says anyone who has returned from those specified parts of Italy and South Korea, as well as Iran, since 19 February should call the NHS 111 helpline, stay indoors and avoid contact with others.
Anyone who has returned in the past 14 days from Hubei Province in China - where the FCO has warned against all travel - should do the same.
People should also call the helpline and self-isolate if they are experiencing symptoms - however mild - after returning to the UK from the following places:
- Vietnam, Cambodia, Laos, Myanmar and parts of northern Italy since 19 February
- Mainland China, Thailand, Japan, South Korea, Hong Kong, Taiwan, Singapore, Malaysia or Macau, in the past 14 days
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