UK Prime Minister Boris Johnson has said he will only impose another nationwide coronavirus lockdown as a last resort, comparing the tool to "a nuclear deterrent" in an interview.

Johnson, who is hoping Britain can return to "normality" by Christmas despite fears of a second wave of cases over winter, insisted the country was getting better at tackling the virus.

The UK has been among the worst-hit countries in the world by Covid-19, registering the highest death toll in Europe.

"I can't abandon that tool any more than I would abandon a nuclear deterrent," he told the Daily Telegraph in a wide-ranging interview to mark the end of his first year in Downing Street. "But it is like a nuclear deterrent, I certainly don't want to use it. And nor do I think we will be in that position again."