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.