LONDON (Reuters) - Prime Minister Boris Johnson intends to bring back Brexit legislation to parliament before Christmas, deputy finance minister Rishi Sunak said on Sunday, adding that shortly thereafter the government would present a new budget.

"The overriding mandate that we have from this election is to get Brexit done ...We will leave the European Union in a matter of weeks, by the end of January. Our intention is to bring the Withdrawal Bill, the legislation, back to parliament before Christmas," Sunak told the BBC's Andrew Marr Show.

Asked why the government planned to enshrine its pledge to boost funding on Britain's National Health Service into law, Sunak said: "I think the NHS, everyone agrees, is the number one priority of the British people.

"It's our number one domestic priority and I think this piece of legislation will just underscore that commitment."

(Reporting by Elizabeth Piper; editing by John Stonestreet)