Gardaí in Dublin are investigating an attack on a young woman in Rathmines overnight.

At around 12.30am the woman (22) was approached from behind and punched - she managed to free herself and raise the alarm.

A man in his 40s was arrested close to the scene - he's being held at Terenure garda station under section 4 of the Criminal Justice Act.

The woman was treated in hospital for minor injuries.