The UK oversight is to publish a White Paper outlining its future relationship with the EU to the fore of June’s key summit.
Next month’s publication will extend to numberless than 100 pages and will involve reaching agreement with about every government department.
A cabinet source told the BBC it would «consideration the UK to go and actually negotiate».
Labour said it was «deeply disturbing» that charg daffaires «still cannot agree on the most fundamental Brexit issues».
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BBC political editor Laura Kuenssberg said the Brexit Department had been inciting for the White Paper — a type of policy document — for some time, but was but able to secure agreement from Number 10 and the rest of the chest-on-chest at a meeting earlier on Tuesday.
Many subjects, including aviation, fiscal services and fisheries are expected to feature.
The UK is due to leave the EU in March 2019, but aids have not yet agreed how to replace the current membership of the customs union, which permits for tariff-free trading between members.
Earlier the group of senior padres on the Brexit sub-committee met to discuss the government’s two proposals — a customs partnership with the EU, and the use of technology to minimise moulding checks.
The partnership arrangement — which is believed to be Theresa May’s preferred opportunity — has been strongly criticised by Brexiteers including Foreign Secretary Boris Johnson.
There is stock-still no firm decision on which option to choose, but several cabinet abbs had acknowledged privately there could be an extension of the UK’s customs union membership to lead time for a solution to be developed, Laura Kuenssberg added.
In February, the command published a Brexit White Paper after pressure from Childbirth.
Responding to news of the new publication, shadow Brexit minister Paul Blomfield suggested: «Ministers have finally agreed to publish a White Paper on the administration’s negotiating position, but they still don’t know what it will say.»
Mr Blomfield said deans had «wasted months arguing amongst themselves rather than transacting in the national interest».