Senior loyalist paramilitaries have warned the Irish government to “tone down” its rhetoric on Brexit because the perceived “Brit-bashing” risks harming peace and reconciliation in Northern Ireland, the Guardian has learned.

Leading figures in the Ulster Volunteer Force (UVF) told Irish officials that talk of frontier posts being attacked by republicans in the event of a hard Brexit, or of a border down the Irish Sea, was “winding up working-class loyalists”, according to sources close to the leaders.

In a recent meeting with Dublin officials, they said the Irish prime minister, Leo Varadkar, was alienating even those loyalists who voted to stay in the EU, by using images of a border post bombed during the Troubles to reinforce Dublin’s insistence on a backstop.

The UVF leaders told the Irish side there was a danger that north-south relations, including those between former loyalist paramilitaries and politicians in the Irish Republic, could be “poisoned” over Dublin’s perceived “Brit-bashing”.

The blunt message from what was one of Northern Ireland’s deadliest paramilitary groups echoes accusations by the Democratic Unionist party that Ireland’s prime minister is raising the spectre of a revived IRA terror campaign to avert a hard border between the republic and Northern Ireland.

One loyalist veteran of talks with Irish governments stretching to before the 1994 UVF ceasefire said while he had nothing but contempt for the DUP, which shores up Theresa May’s minority government in Westminster, all unionists, including remain voters, opposed any outcome that would decouple Northern Ireland from the UK.

The EU has supported Dublin’s insistence on a backstop, which could partly align Northern Ireland with EU regulations while the rest of the UK leaves the bloc.

The Rev Chris Hudson, who acted as a go-between with successive Irish governments and the UVF, said there was “serious disquiet” within loyalist ranks over Irish leaders using an image of an IRA border post attack in 1972 to stiffen EU resolve as talks enter the final phase. “They have had a negative impact within that community and did not play well with the general unionist community,” he said.

The previously unreported meeting between UVF representatives and Dublin officials is understood to have occurred two months ago. Varadkar has continued flagging up the possibility of renewed republican violence.

At a dinner with EU leaders in Brussels this month, he brandished an Irish Times article that revisited the IRA bombing of a border post in 1972 that left nine people dead.

The Irish prime minister is not alone in floating the risk of a renewed terrorist campaign. George Hamilton, the chief constable of the Police Service of Northern Ireland, and Drew Harris, the Garda Síochána commissioner, have issued similar warnings.

A spokesman for Ireland’s foreign affairs department said the government was in regular contact with multiple stakeholders in Northern Ireland and had explained its goal was to preserve peace and keep the border open and invisible.

“The Irish government has ongoing engagement at political and official level with a wide range of political, civil society and community representatives from Northern Ireland,” he said.

“In all such contacts, we have emphasised that our objective in the negotiations is to protect the achievements of the peace process and the Good Friday agreement, which represent the fundamental interests of everyone on the island. There is no question of Ireland or the EU trying to undermine the constitutional integrity of the UK.”