Two more patients have tested positive for coronavirus in England, bringing the total number of UK cases to 15.
They have been transferred to specialist NHS infection centres in Liverpool and London, the Department of Health said.
The virus was passed on while they were in Italy and Tenerife, said England's chief medical officer Prof Chris Whitty.
Ministers have said they expect more cases to emerge.
The new patients are being treated at specialist centres at the Royal Free Hospital, London, and the Royal Liverpool Hospital.
Italy now has more than 400 cases of coronavirus with authorities there reporting that 12 people have died.
And in Tenerife, 168 Britons have been told to isolate themselves at the H10 Costa Adeje Palace hotel.
Globally, more than 80,000 people in more than 40 countries have now been infected.
The new cases in England come as the government is set to launch a public information campaign, which will focus on hygiene and how to prevent the spread of infection.
More than 7,000 people in the UK have been tested for the virus.
Of the 15 to have tested positive, eight have so far been discharged from hospital.
