Dissident republicans have threatened to kill 11 council employees in Londonderry.
Those under threat work as community safety wardens for Derry City Council.
It is understood that steps have been taken to increase their personal security.
The staff are managed by Derry Policing and Community Safety Partnership and deal with low level anti-social and nuisance behaviour.
The threat was delivered via a community worker recognised as someone who has passed on threats from dissidents before.
There has been widespread, cross-community condemnation and calls for the threats to be lifted immediately.
Mayor Brenda Stevenson said: "This is an outrageous attack against Derry City Council staff who are working to protect and serve their local communities. The council is taking the threats very seriously and taking the necessary steps to ensure the safety of its staff. I am therefore calling on those responsible to immediately lift the threat and allow these people to continue with the excellent work they are doing to serve our communities."
Sinn Fein councillor Paul Fleming also demanded that the threat be lifted immediately.
"The threat is a sinister development and the latest in a long line of threats issued against various groups and individuals in the city and district," he said.
"The group behind these threats needs to lift them immediately and the people who give them political cover need to explain the rationale behind them."
The SDLP's Gerard Diver, a councillor and Community Safety Partnership member, said: "Any threat made against them is wholly unjustifiable and should be condemned outright by every right-thinking person in our city and district, and should also be withdrawn immediately."
Deputy mayor Gary Middleton said: "The wardens have been consistent in their duties, providing a much needed service and ensuring that our citizens feel safe. I would like to once again pledge our support to the community wardens and call on those who have issued this threat to withdraw it immediately."