The Prime Minister will also insist that “no final decisions have been taken” on the shape of the UK’s proposed departure ahead of a summit with the leaders of Scotland, Wales and Northern Ireland today.
But Ms Sturgeon has insisted this does not go far enough and is backing her Welsh counterpart Carwyn Jones’ call for the devolved parliaments to have a vote on Brexit.
The SNP leader also wants a “clearly mapped out” programme of involvement in talks amid concerns the UK is heading for a “hard Brexit”.
The First Minister wants a detailed timeline, to ensure that a negotiating position is agreed that reflects the different views across the UK. Her plans come as a new report today warns of “constitutional crisis” in the UK unless a suitable arrangement can be reached between Westminster and the devolved governments over Britain’s departure from the EU.
The new UK government forum, to be chaired by David Davis, will offer a “direct line” to the Brexit secretary, according to Mrs May.
She said: “The great union between us has been the cornerstone of our prosperity in the past – and it is absolutely vital to our success in the future. The country is facing a negotiation of tremendous importance and it is imperative that the devolved administrations play their part in making it work.”
If the devolved governments accept the offer of formal discussions, a new sub-committee of the JMC will be established, chaired by Mr Davis and attended by nominees put forward by devolved governments.
A first meeting will happen by the end of November and at least one more by Christmas as negotiations progress before Article 50 is triggered by the end of March.
Scots voted to Remain in the EU by 62 per cent to 38 per cent, but the weight of votes south of the Border ensured a victory for Leave.
Ms Sturgeon has written to the Prime Minister ahead of today’s meeting warning the UK position will need to “take account of the specific needs, responsibilities and priorities of each administration as part of the overall UK package”.
She added: “To ensure those are properly reflected and the stated position of all parts of the UK as a partnership of equals is respected, I also endorse the proposal that the proposed negotiating package should be subject to a vote in each of the four of the United Kingdom’s parliaments and assemblies.”
A report today by the Institute for Government (IfG) said the four governments should agree the “core planks” of the UK’s negotiating position before the Prime Minister triggers Article 50, or face a “full blown constitutional crisis.”
The IfG warned that imposing a Brexit settlement on Scotland, Wales and Northern Ireland may be legally possible but it would be a “reckless strategy” which could lead to the possible break-up of the UK.