DUP leader Arlene Foster has been described in grossly offensive explicit language in a social media post from the account of an SDLP councillor and party executive member.

Mrs Foster’s photograph — along with the comment “Never mind the beast from the east, here’s a c*** from the north” — was posted into a business WhatsApp group from the account of Dungannon councillor Denise Mullen.

The DUP is calling on SDLP leader Colum Eastwood to take action against the Mid Ulster District Council representative and is reporting her to the local government ombudsman.

The message from Ms Mullen’s account was posted on Wednesday night into the Dungannon Regeneration Partnership’s WhatsApp group. Its membership includes businesses, government agencies and councillors.

The following morning in a message to the group, Ms Mullen apologised for the previous post and said her young son had been playing with her phone while she showered and had accidentally forwarded the image. She said she had removed the image of Mrs Foster as soon as she had become aware of it and had contacted council officers.

When contacted by the Belfast Telegraph yesterday, Ms Mullen declined to comment and referred us to the SDLP Press office. An SDLP spokeswoman repeated the councillor’s explanation of the post and said she had already apologised for any “unintended offence caused”.

However, DUP Mid Ulster MLA Keith Buchanan said he would be contacting Mr Eastwood to ask what action would be taken against her. “This social media post certainly paints a thousand words. This graphic is not designed to critique policies, but rather to stir up hatred of Arlene Foster,” he said.

“The post calls into question Ms Mullen’s position on the Dungannon Regeneration Partnership committee and as an elected representative.

“A complaint has already been made to the chair of the Dungannon Regeneration Partnership and we will be making a complaint to the local government ethical standards directorate, asking them to investigate the matter.”

Mr Buchanan pointed to an interview Ms Mullen had given to the Irish News in 2016 in which she said: “We are trying to get away from hatred and incitement to hatred.”

The DUP MLA said that ”anti-unionist bigotry couldn’t be allowed to go unchecked”. Dungannon DUP councillor Kim Ashton described the social media post as “disrespectful and grossly offensive”. Ms Ashton claimed it would damage relations on the council and on the Dungannon Regeneration Partnership committee. In a post to the WhatsApp group yesterday, Ms Mullen offered her explanation for the offensive message.

“I am truly sorry that a post from someone else forwarded from my mobile phone was placed into our WhatsApp group last night,” she said.

“My young son was playing with my phone while I was in the shower and forwarded on this image. As soon as I became aware of it I alerted council officers and ensured that the image was removed. As you know on council, I work with all parties and have the utmost respect for all people in our community.

“This was an innocent mistake and I apologise for any hurt and offence that it has caused. I trust you will accept my apology and convey my sincere comments to your colleagues.”

An SDLP spokeswoman said: “Councillor Denise Mullen has informed us that her young son while playing with her personal mobile phone accidentally forwarded on an image of an online post that included offensive language relating to the DUP leader on WhatsApp.

“Cllr Mullen explained that as soon as she became aware she had the image removed. The SDLP understands that Cllr Mullen contacted council officers immediately and has issued a full apology to the DUP for any unintended offence caused.”

Ms Mullen has served on Mid Ulster Council since 2014. She also sits on the SDLP’s ruling party executive and is a member of the South Tyrone Policing and Community Safety Partnership. Her father Denis was murdered by the UVF’s Glenanne gang at his home in the Moy in 1975.

Belfast Telegraph