The former N-Dubz singer Dappy has been found guilty of assaulting a man at a nightclub.

The 27-year-old, who was tried under his real name of Costadinos Contostavlos, denied attacking Devonn Reid during a public appearance at the Evissa club in Reading, Berkshire, on 6 October last year.

The singer committed the offence while serving a six-month suspended sentence for a previous affray and assault, which could now be activated.

District Judge Davinder Lachhar told Reading magistrates court: "Custody is a realistic prospect as far as this case is concerned in light of his record."

The court heard the fight broke out because Contostavlos began chatting to Reid's female friend and girlfriend at the club's bar, and that the singer punched him after Reid told him not to talk to them.Contostavlos arrived at the court wearing dark sunglasses, a white shirt and black trousers and posed for "selfie" photos with friends in the corridor outside the court.

Giving evidence, the singer said he had gone to the club with a small group of friends at around midnight on 5 October and initially went to a private seated area.

Describing the mood as "very happy", he said: "It was splendid to be there. It was a very good night, everyone was polite to me and I was being polite back, showing lots of love, taking pictures. It was a good vibe."

Asked by his defence barrister, Jon Harrison, whether he had punched Reid, he replied: "Certainly not".

But prosecutor Zainab Mohamed suggested he had been "humiliated" when Reid and his friends did not want a drink with him and warned him off talking with the women in the group.

She said: "You were angry, you were humiliated, you had been drinking alcohol during the evening and you became annoyed at the aggrieved [Reid] when he told you not to talk to them … Because you were angry you in fact punched the aggrieved in the nose."

Contostavlos denied hitting Reid, saying it was "two of us and seven boys, and that he was scared because he was outnumbered and they were bigger than him.

But Lachhar said she found the witnesses, who included Reid's girlfriend Cydney Webb and friend Marie O'Reilly, to be truthful, and found him guilty of assault by beating.

She said: "There is a question of who assaulted him [Reid] and in my mind I have no doubt that you did."

Contostavlos sat with his head in his hands as he realised he could be sent to prison following his conviction for the attack, which occurred while he was serving a six-month sentence, suspended for 18 months, for a previous incident of affray and assault.

A trial last year heard he sparked a "mob-handed attack" when he spat at two women at a petrol station in Guildford in February 2012. The pop star was also fined £800 in June this year for lashing out and slapping a man at a nightclub in Chelmsford, Essex, in February.

Contostavlos was bailed to 6 October, when he will be sentenced for the assault in Reading.

An investigation is also under way into a possible contempt of court after a photo of a witness at Friday's trial was posted on social media. It is illegal to take photographs in a court.