The National Council for Voluntary Organisations has declined to endorse a statement from other charity representative bodies calling for the UK to remain in the European Union’s single market and the customs union.
The Scottish Council for Voluntary Organisations, the Northern Ireland Council for Voluntary Action and the Wales Council for Voluntary Action issued a joint statement today listing a series of proposals to "minimise potential harmful impacts" of Brexit on the third sector and wider society.
Top of the list was for the UK to remain in the single market and the customs union, measures the government appears to have ruled out.
"We believe that this outcome is vitally important for protecting the peace process and preventing the major economic and social impacts for people and businesses that would be presented by the creation of a hard border," says the statement.
But the NCVO declined to add its name to the document.
A spokesman for the NCVO said that, although the proposals would be effective, there "may be other ways" of proceeding and therefore "we don't want to commit to those specific solutions at this stage".
He added: "We will continue to press the government to ensure that they deliver the best possible outcomes for the sector."
The three other national third sector bodies said they had "serious concerns that leaving the European Union will exacerbate already difficult circumstances" for not-for-profit organisations.
Besides arguing to stay in the single market and the customs union, they called for "a sufficient transition period to minimise confusion and uncertainty", even if this goes beyond the government's aim of leaving the EU in 24 months.
The statement also called for civil society to have a stronger voice in shaping Brexit decisions, no regression on workplace rights, gender equality and other rights after Brexit, a ring-fencing of funds repatriated from the EU "for the key social policy themes" and for the UK voluntary sector to maintain EU connections.
Lucy McTernan, acting chief executive of the SCVO, said in a statement: "Many of the people third sector organisations represent fear a weakening of the rights and protections they currently enjoy as EU citizens and worry that their voices will not be heard in negotiations.
"We believe that the UK needs to stay in both the single market and the customs union to keep the economy strong, ensure free movement of people, secure important funding, maintain hard-won rights and allow us to continue building partnerships and learning from our friends and colleagues across the continent."
Seamus McAleavey, chief executive of Nicva, said the next phase of Brexit negotiations would have "major implications for the lives of everyone in Northern Ireland and the more than 30,000 people who cross the border daily".
He added: "It is vital that solutions are found to ensure no hardening of borders on the island or with Great Britain and which do not undermine the peace, stability and cooperation brought about by the Good Friday Agreement in all its parts."
Ruth Marks, chief executive of the WCVA, said: "Whilst each devolved nation will have its own domestic concerns about Brexit, it is important that we work together as a sector to better engage with and positively influence the crucial debates that lie ahead."
A WCVA spokeswoman told Third Sector it was apolitical and the views represented members' concerns. A survey of WCVA members, carried out last year, revealed that three-quarters felt EU funding to charities had made a big difference to Wales.
The spokeswoman said the proposals would be sent to politicians in the devolved nations and at Westminster.