U.K. Brexit Secretary David Davis said the U.K. is unlikely to agree by October a figure with the European Union for the former's divorce bill, Reuters reported.

The parties need to decide how the exit bill will be calculated before commencing negotiations about the U.K.'s trade relationship with the EU.

"We're going to talk it through very, very carefully, so at this stage we're not going to commit, there won't be a number by October or November, whenever it is," Davis told BBC radio.

He added that any transition period should be completed by May 2022, when the next general elections in the U.K. are due to be held, but was likely to last for about two years after Brexit. This comes amid reports that the U.K. wants to remain in the EU's customs union for a transition period after leaving the bloc.