The leader of a now-disbanded youth gang, who is on trial for raping a 13-year-old girl on four occasions between November 2013 and January 2014, denied yesterday that he had ever laid a finger on her.

"I did not touch her," salesman Koh Rong Guang, 25, who is also known as Charles, told the High Court as he took the stand to give his version of events for the first time on the fifth day of his trial.

He said the girl made up the allegations because she wanted to get him into trouble for posting photos of her in sexually explicit poses with his "best bro" in the gang, Fu Yiming, 20.

Koh said he had told someone else to upload the photos, which later went viral, to shame Fu for ratting him out to the police in a rioting case.

He said he did not like the girl, whom he described as a "stranger" and a "slut" who tried to get close to Fu even though he had a girlfriend.

Koh is accused of pinning the girl down and raping her on one occasion in late 2013. But he said that incident never happened.

Instead he and his then-girlfriend had confronted the girl for badmouthing Fu's girlfriend, he said. He added that his then pregnant girlfriend - now his estranged wife - slapped the girl, who cried and left.

Prosecutors, however, accused Koh of using the girl, who is now 17, as a "sex toy".

Deputy Public Prosecutor David Khoo, citing exchanges of text message between Koh and Fu, told the court that in the lead-up to one incident Koh had told Fu that "whatever I want (to) do to her you cannot interrupt".

DPP Khoo contended that the messages showed that Koh had the intent to have sex with her.

DPP Khoo also said that Fu and two other youths had corroborated the girl's testimony that Koh had sex with her. The prosecutor asked if Koh was saying that the four witnesses had met and agreed to say the same thing.

"Yes. This is what we did in the rioting case," Koh replied.

Koh faces 12 charges - four of statutory rape, one of sexual assault by penetration, three of criminal intimidation, two of committing an indecent act with a young person, one of causing hurt and one of circulating a nude photo of the girl.

The alleged rapes took place at the staircase of a karaoke outlet in Choa Chu Kang Centre and the staircase of a block of flats in Choa Chu Kang Crescent.

The girl made a police report in July 2014, after the sexually explicit photos trended on social media platforms.

Yesterday, Koh denied taking those photos, saying he was not at the scene. He said Fu was the one who sent him the pictures, which he assumed had been taken with a self-timer. He also denied taking a nude photo of the girl, claiming that one of the boys she had slept with had sent it to him.

He also told the court that he was not calling his estranged wife and other witnesses to support his account, saying that he was now on "bad terms" with everyone.