A man in his 20s sustained serious head injuries in an assault in Dublin city centre in the early hours of Saturday morning.

Gardaí in Pearse Street are appealing for witnesses to the assault, which happened at the junction of Aston Quay and Westmoreland Street, Dublin 2, on Saturday 29 June at 3.50am.

The injured man was taken to St James's Hospital after the "serious assault", gardaí said.

It is believed the assailant was not wearing a top.

The attacker travelled on foot across O'Connell Bridge, turned left towards Bachelors Walk and then took the first left heading towards Bachelors Way, gardaí said in an appeal.

They are looking for any witnesses to come forward, as well as anyone who may have observed anything suspicious on O’Connell Bridge or in the directions of Bachelors Walk and Bachelors Way after 3.50am on 29 June.

"We are also appealing to any motorists who may have dash-cam footage and travelled these routes from 3.50am onwards," said a garda spokesperson.

Anyone with information is asked to contact Pearse Street Garda Station on 01 6669000, the Garda Confidential Line on 1800 666 111 or any garda station.