An investigation is under way into an alleged serious sexual assault in Phibsboro in Dublin.

A woman was allegedly attacked by up to three men in a laneway beside a convenience shop across from St Peter's Church at Cabra Park, Phibsboro between 7.15pm and 8.45pm on Sunday. 

Three men are believed to have been involved in the incident.

The main culprit involved is described as being 1.75cm (5'9") tall, of skinny build with shaved blonde hair with a light facial stubble.

The man is also described as having facial scarring, and was wearing grey cotton trousers with a white stripe down the side, a grey jumper with a hood and black runners at the time of the assault.

The second man is described as being 1.83cm (6') tall, with a thin face with dark eyes, and was wearing a dark grey hooded sweatshirt. 

He also has what is described as a distinctive scar on his left hand.

No description is available for the third man.     

The woman was taken to the Sexual Assault Unit at the Rotunda Hospital.

No arrests have been made.

Gardaí are particularly anxious to speak to a man who may have met these men in the laneway following the alleged incident.

They are also appealing for anyone who may have witnessed the incident or who may have information to contact them at Mountjoy Garda Station on 01-6668666 , the Garda Confidential telephone line on 1800-666111 or at any garda station.