One of the Northern Ireland fans beaten with baseball bats in Slovakia has had a testicle removed and is under observation by doctors at Belfast City Hospital.

Gareth Marcus, 18, was set upon in the main square of Bratislava by a group of up to 15 men thought to be bouncers – just hours before their team took on Slovakia in a weekend World Cup qualifier.

When Gareth arrived home in Northern Ireland, doctors told him they needed to operate. When he woke from surgery he was told the bad news.

Gareth from south Belfast told the Sun: "The TV cameras came along and were asking us to keep singing.

"Five minutes after the cameras left it all kicked off. The whole attack was unprovoked.

"I saw 12 big fellas running around. Three of them came at me. They just emptied me.

"I got hit across the face. I don't know what happened to my testicles - they may have been punched or stamped on."

"I went to hospital on Sunday. The urologist thought it was just cracked. But after the op he told me it was completely crushed and needed to be removed."

Spokesman for the Amalgamation of Official Northern Ireland Supporters Clubs Gary McAllister described the teenager’s plight as “sickening”.

Anthony Gavin (29) and Matthew Ogle (23), were also among the group that suffered injuries in the brawl. A number of others were left badly shaken by the terrifying ordeal.

Mr Gavin, from Maguiresbridge, lost seven teeth and his left eye was closed over after his face was smashed. His pal, Matthew, also needed medical attention for an eye injury. Matthew said they were attacked for singing.

“The boys said they were at the Dubliner enjoying themselves. Yes, they were singing but then all of a sudden these big men – really big I’m told – stormed into the bar and attacked at will,” said IFA president Raymond Kennedy.

The Irish Football Association have promised to fully investigate the incident. A spokesman for the British Embassy said Slovakian police were investigating the incident.