Two Northern Ireland women said they were punched, kicked and spat on by a group of young teenage girls at a Westlife concert.
The sisters said they were completely humiliated by the ordeal
The sisters - one of whom had flown from Spain especially for the concert - said they were appalled by the conduct of staff who they said stood by and let the incident happen.
The police said they were investigating a complaint of an assault at the Odyssey Arena in Belfast during the concert on Sunday night.
Frances and Emma Stroud from Belfast had spent £36 each on the Westlife tickets and had attempted to take up their seats at the concert.
However, they said three girls joined another girl in the row and the four attempted to share two seats.
Frances, a 22-year-old trainee teacher, told BBC News Online she and her sister had been completely humiliated by the entire incident.
"The four girls were sharing two seats between them and the whole way through the concert they were digging Emma in the side and trying to push her out of the way because there wasn't enough room."
She said one of the girls, who was aged about 13, was swearing at her and her sister and pushed 18-year-old Emma.
'Asked to see tickets'
"The two of us went flying out of the row and she then punched Emma in the side.
"We asked her to stop, but she then hit me a full dig on the nose and whacked me round the side of the face with a plastic glow stick.
Frances Stroud said she was punched, kicked and bitten
"I tried to take it off her, but then her friends got up and started to punch me in the face."
Frances said two security guards pushed her and Emma into the row.
"I said: 'I can't move in, because there is no room for me to move into'. The security guard screamed in my face: 'If you don't get into the row I'm going to throw you out'."
She told the security guard about being punched in the face and being hit with the glow stick. She said the guard told her "he was not really bothered".
Another member of staff asked to see their tickets and was satisfied they were in the correct seats. However, when the younger girls said they did not have any tickets for the seats they were just told to squeeze up.
They said they would not hit back because the girls were much younger than they were.
'In a terrible state'
Frances said that in a further bout of aggression from the young girl, the security guards "were all standing there laughing".
"I went over to them and asked were they not watching this, and one of them said: 'We don't really care - cheer up and give us a song'.
"The girl was spitting in my face and I put my arm up to stop her from punching me - I couldn't hit her back because she was only young - and she bit my arm."
Westlife were playing two nights at the Odyssey arena
The girls said the security guards dragged them out of their seats and rushed them out of the Odyssey just before the end of the concert.
"Westlife were right in front of us on the stage and would have seen this big rumpus going on."
The women's mother, a school principal, said she had to comfort the girls during the night because "they were in a terrible state".
She said she had contacted the Odyssey on two occasions to make a complaint, but was told she "would have to put something in writing".
A spokesman for the Odyssey said: "We are fully investigating this internally.
"We have established a number of facts, including the fact that the incident was reported to the police.
"Unfortunately, the lady who took the incident report is off for a few days and we are trying to contact her."
He said the Odyssey intended to cooperate with any police investigation into the incident.