Both cases are believed to be connected and there is a link to southern Africa.
Health Secretary Sajid Javid said targeted testing is now being carried out, as travel restrictions were set to be introduced for Malawi, Mozambique, Zambia and Angola.
Prime Minister Boris Johnson is expected to set out further measures during a Downing Street press conference later on Saturday.
This is a breaking news story and more will be added as it comes in
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