Four people have been arrested in connection with a brutal assault on a young man in Dublin last weekend.

The man - aged in his 20's - was found with serious head injuries at Lamb Alley in Dublin 8 at around 1.30 on Sunday morning last. He was initially brought to St. James' hospital but was subsequently transferred to Beaumont Hospital where he is still in a serious condition.

Two men and two women - all aged in their 20's - were arrested in connection with the attack this morning and are being questioned at separate Dublin Garda stations.

Meanwhile Gardai are also appealing for any witnesses to the assault to come forward, they're particularly anxious to speak to a taxi driver who picked up 2 men in the Meath St. area of Dublin at around 1.15 am on Sunday and dropped them nearby on Francis Street.

Its understood the taxi may have been a dark coloured Opel Insignia or similar type saloon.