A death threat has been made against a Belfast-based journalist by a loyalist paramilitary group, the National Union of Journalists has claimed.

The union has condemned the threat, which it initially said was was made by the Ulster Defence Association against an investigative journalist, although the group has now denied this.

The journalist and the organisation he works for has not been named by the union but graffiti with his name and mobile number was placed in locations in Belfast.

A statement from the UDA has said it does not condone or take responsibility for the threats and this has been given a cautious welcome from NUJ bosses, who have offered to meet with the Ulster Political Research Group, which is an advisory group connected to the UDA.

Irish NUJ Secretary Seamus Dooley said the Police Service for Northern Ireland was taking the threat seriously, which he said was part of a “sinister campaign”.

He said: “This represents the latest threat to this journalist and is part of a sinister campaign which must be condemned. A free press is the cornerstone of a democratic society and peace cannot be said to exist when journalists are faced with death threats.”

NUJ General Secretary Michelle Stanistreet said: “We take the death threat against our member very seriously. The fact that he was named in graffiti along with his mobile phone number on strategically placed locations is a clear indication of the intention – the intimidation of an investigative journalist.

“The very direct threat to his life cannot be ignored. In so far as the UDA statement we are giving it a guarded welcome.”

A spokeswoman for the union said it was not releasing further details and would not say whether the person who was threatened was a newspaper journalist.