A Sinn Féin Assembly employee has resigned after admitting involvement in an incident where a DUP portrait was damaged at Belfast City Hall.
The republican party, which has been rocked by a number of recent controversies, said police have been informed.
An investigation had been launched after the official portrait of former DUP lord mayor Lord Browne was damaged.
The DUP said the portrait was removed from a wall and the glass in its frame smashed.
The incident happened following an event on Saturday evening to celebrate an Irish language group’s 20th anniversary.
It comes just days after a portrait of former Belfast lord mayor Niall O Donnghaile was removed from City Hall after revelations that he had quit Sinn Féin last year after the party received complaints that he had sent inappropriate texts to a teenage party member.
Sinn Féin leader Mary Lou McDonald has faced pressure over a statement she made to the Dáil last week about senator Mr O Donnghaile.
In a statement released on Monday evening, a Sinn Féin spokesperson said: “Today, 21st October, a Sinn Féin employee, who works in the Assembly, made the party chief whip aware of their involvement in an incident regarding a portrait in Belfast City Hall which took place on Saturday 19th October.
“The employee was immediately suspended, and we have notified the PSNI today.
“The employee has now resigned from their employment and their party membership.”
Dean McCullough, the DUP’s deputy group leader on the council, told the BBC: “It is disgraceful.
“The ripping off of the portrait of former lord mayor Lord Wallace Browne is disgraceful.
“There is no equivocation between the removal of the (O Donnghaile) portrait which our party led on and called for.
“Lord Browne is a well-liked and well-respected politician.
“We have called for a full and robust investigation because there are a number of outstanding questions.”
The damage was caused following an event organised by the group Glór na Mona said they were “extremely disappointed” about the incident and would assist the council with its investigation.
A social media post from the Irish language group said: “Following the formal end of our event, a portrait within City Hall was damaged.
“Glór na Mona had no knowledge of this taking place and only became aware of this on Monday October 21 when contacted by council staff.
“This is completely contrary to the ethos and principles of our organisation and the spirit of our successful anniversary celebratory event.”
A spokesperson for Belfast City Council said it hoped the necessary repairs would be carried out as soon as possible, so the portrait can return to display.
They said: “The portrait of former lord mayor, Lord (Wallace) Browne of Belmont has been removed from public display after it was damaged over the weekend.
“We are currently assessing the extent of the damage and looking into the circumstances which led to the portrait being damaged.”