Update 7.55pm: Katie was located safe and well this evening.
Update 12.15pm: Gardaí in Dun Laoghaire are asking for the public's help in finding a 17-year-old girl.
Katie Hughes was last seen on Sunday at around 5.30pm in Dun Laoghaire.
She is described as being five foot six inches tall and of slim build.
When last seen she was wearing a black zipped hooded top, black boots, a black jacket and denim shorts.
Anyone who has seen Katie or who can help to find her is asked to contact Dun Laoghaire Garda Station on 01 6665000 or any Garda Station.
- Digital Desk