The attack comes from the Northern Ireland Local Government Association (NILGA), which says it will raise its concerns about the Irish border when the UK leaves the EU with the Committee of the Regions.
The move comes with formal Brexit negotiations between the two sides expected to resume next week.
The EU has insisted that the Irish issue, along with the UK's divorce bill and citizens' rights, must be resolved before the talks can progress.
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The UK government has just published proposals for an unprecedented solution to the Irish border, with wide-ranging exemptions from any new tariffs for small and medium-size firms after the UK leaves the EU.
Border checks are not optional for a country outside the customs union. They are required under EU law.
Authorities will have to find a way to monitor the 310 mile-long border and its network of up to 200 invisible crossing points.
Derek McCallan, chief executive of NILGA commented, "We need stronger assurances from government about what this is all leading to - clear options for key partner bodies in manufacturing, farming, local government, construction, and so on, to comment upon - what reality will look like for local people and businesses.
"The increasing disconnect between what is going on in London and the delivery of services on the ground here must be halted and we cannot have a shift back to centralist policies and decision making
"We are calling for councils to be given real powers and real resources as part of solving this widening democratic deficit - before we are literally disempowered and made uncompetitive as an economic region."
A European Parliament briefing to MEPs last month stated that "the Northern Ireland PEACE programme will form part of the discussions that are to take place during the upcoming negotiations between the UK government and the European Union."
Ireland's Prime Minister, Leo Varadkar, had urged Theresa May to remain in the customs union to avoid border checks.
McCallan was speaking ahead of another UK position paper due to be published later this week that will explore what judicial arrangements might govern the UK's relationship with the EU after Brexit.
On this, the UK's Secretary of State for Exiting the EU David Davis said, "Our position has always been clear: in leaving the EU, we will bring about an end to the direct jurisdiction of the Court of Justice of the European Union.
"While we believe this will likely require a new and unique solution, our paper will examine a number of precedents. We're not being dogmatic in our approach but building on existing precedents to find a solution."