LONDON - More than three-quarters of British firms that took part in a Bank of England survey expect uncertainty about Brexit to last until 2021 at least, the central bank said on Thursday.

"Businesses expect uncertainties around Brexit to take longer to be resolved than in the January survey," the BoE said as it published the Monthly Decision Maker Panel (DMP) survey of chief financial officers.

"In February, 76% of businesses expected uncertainty to persist until at least 2021. That proportion had risen from 59% in January, continuing a trend seen over recent months."

Prime Minister Boris Johnson has said he will secure a trade deal with the European Union before a deadline of Dec. 31, a timetable that many trade experts say looks tight.

The February DMP survey was conducted between Feb. 7 and Feb. 21 and was based on 2,891 responses.

(Reporting by William Schomberg, editing by David Milliken) ((william.schomberg@thomsonreuters.com; +44 207 542 7778; Reuters Messaging: william.schomberg.reuters.com@reuters.net))