Five police officers yesterday refuted claims by a man accused of raping a 16-year-old girl that he was tortured and threatened after his arrest.

Former pizza delivery man Muhammad Firman Jumali Chew - who allegedly posed as a police officer before the alleged rape - testified last week that he was "bashed" against a wall, stripped naked and had ice water poured over him in an interview room at the Police Cantonment Complex.

He said that Criminal Investigation Department officers tore his shirt and threatened to make his mother lose her job and to send his wife back to the Philippines.

There were 10 officers in the room, who showed him a DNA report and a CD of surveillance footage and told him to confess, he said.

On the sixth day of Firman's trial yesterday, the five officers took the stand to deny his allegations.

The court heard that Firman first raised allegations of abuse in the State Courts on Oct 12, 2013 when he was charged, but did not want to make a police report.

An internal investigation was conducted but no further action was taken, according to Assistant Superintendent (ASP) David Ang, the investigating officer of Firman's case.

Inspector Thinagaran S. Krishnasamy said that as he was escorting Firman into the room, the suspect's steps quickened. He said he misinterpreted this as Firman "trying something", so he pulled him back, accidentally tearing his shirt.

According to the officers, the room was between 4 sq m and 6 sq m, and could barely fit five people.

Firman, a Singaporean, is accused of identifying himself as a police officer to a teenage couple he observed having sex in a Woodlands HDB stairwell on Oct 9, 2013.

He allegedly sent the boy away and led the girl to another block where he allegedly raped her. His semen was found on her underwear and his identity was established through his DNA profile.

Firman was arrested at Woodlands Checkpoint on Oct 11, 2013.

He faces one charge each of rape, sexual assault and impersonating a police officer.

The court also heard that between 2006 and last year, Firman made over 100 police reports complaining about people stealing Wi-Fi and following him, among other things.

This arose from his claim that he made police reports against lift technician Tung Shue Kiong - a passer-by who confronted him on the day of his alleged offences.

In court, Firman portrayed Mr Tung as a pervert who loitered around to spy on couples.

ASP Ang said he could not find any report by Firman that involved a culprit matching Mr Tung's description.

Both sides are to submit closing arguments by June 15.