The figure was announced as part of Britain's 2017 budget
Britain has announced an extra £3bn (€3.38bn) of funding to prepare for its departure from the European Union.
The figure was announced by the British Chancellor of the Exchequer, Philip Hammond, as part of his Budget 2017 speech.
The Brexit fund will be put in place over next two years.
During his speech in London, Mr Hammond said Brexit negotiations are in a "critical" phase.
"We are determined to ensure the country is prepared for any possible outcome", he said.
Also announced as part of the budget was over £650m (€731m) for a new Northern Ireland executive, stg£2bn (€2.25bn) more for the Scottish government and £1.2bn (€1.35bn) more for the Welsh government.
It comes as British Prime Minister Theresa May says she believes devolved government for Northern Ireland at Stormont can still be achieved.
Mrs May held talks with delegations from both Sinn Féin and the DUP in London on Tuesday.
The two parties have been locked in talks with no sign of agreement, and the Stormont Executive has not sat since January.
Speaking after the meeting at Downing Street, Mrs May said: "While not in any way underestimating the challenges involved, I believe that a way forward can be found and an agreement reached."
Separately, reports say a stg£10.6bn (€11.97bn) budget for Stormont is expected to pass the Houses of Commons and Lords, and enter into force later this week.
In his budget speech, Mr Hammond also presented revised GDP growth estimates for 2017 for Britain - down to 1.5% from 2% and down to 1.4% from 1.6% in 2018.
He said British debt was still too high and stressed the "need to get it down".
Additional reporting: IRN