A very significant expansion of the number of cases of coronavirus in Britain is "clearly on the cards", Prime Minister Boris Johnson said on Monday.

The United Kingdom so far has 40 confirmed novel coronavirus cases. Earlier Johnson said Britain was very well prepared and would be making "every possible preparation".

"The most important thing now is that we prepare against a possible very significant expansion of coronavirus in the UK population and that is clearly on the cards," Johnson told the BBC in an interview.