SINGAPORE - The doctor involved in the HIV registry data leak told a court on Thursday (July 25) that he was "afraid" of being penalised under Section 377A of the Penal Code for providing prostatic massages, and decided against telling narcotics officers about it.

The law criminalises sex between consenting adult men.

Ler Teck Siang, 38, is accused of injecting narcotics into abusers for a fee in a practice known as "slamming".

He had denied providing the drug injections earlier in the trial, claiming that he had instead given sports and prostatic massages to drug abuser Sim Eng Chee.

Sim, who is serving a sentence for drug consumption and possession, had testified that he hired Ler for "slamming" services before sex parties with other men.

On the sixth day of Ler's trial, the medical doctor told a district court that he did not mention this prostatic massage services to narcotics officers as he was "not certain if it would constitute" an offence under Section 377A in the Penal Code.

He said he did not provide such services in the "capacity of a medical professional", adding that he was embarrassed that he did offer prostatic massages.

"It's a private and personal kind of service I was providing... not something I'd want to share with a narcotics officer," said Ler.

He is contesting one charge of injecting methamphetamine, also known as Ice, into Sim on Feb 26 last year, and another charge of possessing drug-related utensils a few days later on March 2. Sim's age was not mentioned in court documents.

Narcotics officers had allegedly found a methamphetamine-stained syringe and straws on Ler when they arrested him and Sim at Conrad Centennial Singapore.

Ler claimed on Thursday that he had provided "health advisory services", which included the massages, to Sim on those two occasions.

The "primary aim" was to change the dressing on Sim's wound on his left arm, he said.

Sim's wound was mentioned in a previous hearing. He had previously testified to seeing Ler for medical advice about the wound.

On Thursday, Ler's former business partner - Dr Ng Tsorng Chinn, the director of Faith Medical Group - took the stand to testify that Ler was a "good man".

Ler, who is representing himself, asked Dr Ng to explain what the syringe Central Narcotics Bureau officers found on him is typically used for.

Dr Ng said it is meant for subcutaneous injections like when injecting insulin, adding that it is "too soft, too small, too short," to be used for intravenous injections. "Slamming" involves intravenous injections.

Ler's friend Lefebvre Chris Bryan also took the stand to testify that he was present on the two occasions when "slamming" sessions allegedly took place involving Sim.

He said he saw Ler only dress Sim's wound and did not witness Ler administering drugs into Sim.

However, during cross examination, Deputy Public Prosecutor Nicholas Wuan charged that Mr Lefebvre was lying to protect Ler, noting that he was in court because of his close relationship with Ler.

Mr Lefebvre denied this.

The trial will resume in August.

Both Ler and his former American partner, Mikhy Farrera-Brochez, are at the heart of the HIV registry data leak where details of 14,200 HIV-positive patients here were leaked online.

Farrera-Brochez was found guilty of three charges against him relating to stolen identification documents from Singapore by a US court on June 4 and will be sentenced on Sept 27.

The Ministry of Health also has a civil suit ongoing in Kentucky to compel him to delete and return the stolen HIV Registry data.