Three girls have been found guilty of carrying out a "happy slapping" sexual assault.

The victim, who cannot be named, was 17 at the time of the ordeal and is now 18.

He sobbed as he recalled the incident to the court.

Judge Colin Smith described the three-and-a-half-hour attack, which took place in a block of flats in Woolwich on March 28 last year, as a "disgraceful episode".

The victim told how the girls stripped him to his socks between punches, kicks and repeated beatings with a broom.

They also forced him to commit a sex act on himself.

He had been dragged to a flat by one of the attackers, who accused him of owing her money.

One of the girls filled a bath with cold water while others were filmed on a mobile phone smearing him with oil and tomato sauce.

He was then made to climb into the bath and wash the mess off.

The youth also said he was forced to do press-ups and star jumps in the kitchen.

After the attack he said his clothes, which had been thrown off a balcony during the assault, were returned to him and he was allowed to dress and leave.

He was later treated in hospital for cuts and bruising.

The court heard the teenager could not escape due to a leg injury and because his upbringing "not to hit women" stopped him fighting back.

He said even after the phone video was sent to members of his family, death threats prevented him from going to the police for several weeks.

Investigating officer Detective Constable Neil Perkin said: "The perpetrators filmed out these crimes, commonly known as 'happy slapping' videos, and showed absolutely no humanitarian decency towards him."

The girls - two aged 17 and one aged 16 - were found guilty at Inner London Crown Court of false imprisonment and causing a person to engage in sexual activity without consent.

One of the gang had pleaded guilty to assault causing actual bodily harm and the other two were found guilty of the same charge on August 9.

One girl was acquitted of kidnapping and all three were cleared of theft.

A fourth girl, aged 17, was acquitted on all counts.

The convicted trio, who also cannot be named for legal reasons, were remanded in custody and are set to be sentenced on August 30.