Devolved administrations write to UK Government on review of relations.
The Scottish and Welsh governments are urging an end to delays in reforming their relationship with Westminster.
In a joint letter to UK Cabinet Minister David Lidington, they call for immediate steps to improve the current “weak and ineffective” government structures, guarantee respect for devolved responsibilities and strengthen the dispute resolution process.
The move follows a written statement from Mr Lidington setting out draft principles on intergovernmental relations.
Constitutional Relations Secretary Michael Russell said:
“It is deeply disappointing that the intergovernmental relations review commissioned 15 months ago has made so little progress. The proposed principles bear little meaning without any firm commitments for further reform.
“This is urgent. By early November the UK could be embarking on negotiations on future relations with the EU27, or new international trade agreements, or both. We need to see a step change in approach to the future partnership, and to all international negotiations which impact on devolved competence, so that our roles and responsibilities are fully respected.
“The Scottish and Welsh governments have made clear how we expect to be involved in these matters, now and in the future. It is absolutely vital that we have agreed the way forward before any UK negotiating mandates are set and any negotiations proceed.
“Whether or not the UK leaves the EU, there is an urgent need for fundamental reform of the relationship between our governments.
“A Heads of Government meeting should be convened as soon as possible to agree a programme for change and a clear timetable.”
A copy of the letter from Constitutional Relations Secretary Michael Russell and Welsh Counsel General and Brexit Minister Jeremy Miles, is attached.