LONDON (Reuters) - A trade deal between Britain and the European Union will be difficult to conclude by the end of the year if a broad agreement has not been reached by October, cabinet office minister Michael Gove said on Thursday.

"If we haven't secured significant progress by October, then it will be difficult," Gove said. He added that there was no formal cut off date beyond which a deal could not be implemented.

Any deal would require ratification by both sides - a process which could take several months in the European Union.

(Reporting by Guy Faulconbridge and Kate Holton, writing by William James)