A man and woman dressed as Batman and the Joker are being hunted by police after two teens were violently assaulted in a suspected knife attack.

They were captured on CCTV looking like the comic book characters just moments before the two 18-year-old men were injured in the 'unprovoked' attack, police said.

One man was left with 'serious facial injuries' and needed hospital treatment, while the second suffered a slash wound to the hip.

South Yorkshire Police said the nature of the injuries suggested a knife had been used in the attack.

Officers probing the incident have released still images from CCTV footage which show a man with short mousey coloured haired wearing a black t-shirt with a Batman logo.

He is accompanied by a woman in a low cut purple top and make-up mimicking that of the iconic Joker character, depicted on screen by Jack Nicholson and Heath Ledger.

The attack took place just after 3am on October 30, when three men left Stein Haus Bar on West Street, in Sheffield.

The group was followed onto nearby Bailey Lane by the man wearing a Batman t-shirt and the woman dressed as the Joker before they were 'violently assaulted'.

The force has urged anyone who recognised the man and woman to get in touch.