Francesca O'Brien, the Conservative candidate for the Gower constituency in the forthcoming UK elections, said that people appearing on the TV show "Benefits Steet" needed "putting down".
In the posts following the broadcast of the first episode of Benefits Street five years ago, Ms O'Brien said: "Benefit Street..anyone else watching this?? Wow, these people are unreal!!!"
Responding to another user's comment, she said: "My blood is boiling, these people need putting down."
In a statement released on Sunday, Ms O'Brien said: "These comments were made off the cuff, a number of years ago.
"However, I accept that my use of language was unacceptable and I would like to apologise for any upset I have caused."
Benefits Street was a Channel 4 documentary about people on welfare, broadcast in 2014, criticized at the time for "vilifying and misrepresenting benefits claimaints" in tabloid fashion. O'Brien neglected to delete her social media history before launching her bid for office.