The Taoiseach says that tweets posted by a newly elected Sinn Féin TD should "trouble us all."
Réada Cronin has apologised for a series of tweets she posted in the years before she was elected.
In her tweets, she linked Israel to Nazism, questioned the fluoridation of the public water supply, and used offensive language.
She also replied to another Twitter account which suggested "loads of judges are paedophiles" by saying "wouldn't surprise me".
Leo Varadkar has criticised her remarks saying that Sinn Féin is "not a normal party" and that their mask has slipped again.
The Kildare North TD has apologised and says she "never intended to cause hurt or distress to anyone."
Her Twitter account has been locked.