SINGAPORE - Two officers from the Central Narcotics Bureau (CNB) accused of intentionally obstructing the course of justice in an incident involving urine sample tampering are claiming trial.

On Monday (July 5), a district court heard that the pair - Muhammad Zuhairi Zainuri, 32 and Abdul Rahman Kadir, 45 - had allegedly worked with Mohamed Hafiz Lan to tamper with the urine sample of a 32-year-old man identified as Maung Moe Min Oo.

The trio are said to have done so to avoid going through the process of processing Maung, a Singaporean, who was not cooperative in providing a urine sample.

Hafiz, then 41, was sentenced to 18 months' jail last August after pleading guilty to a charge of intentionally obstructing the course of justice.

Zuhairi and Abdul Rahman have been suspended since July 2019.

In their opening statement, Deputy Public Prosecutors Alan Loh, Thiagesh Sukumaran and Rashvinpal Kaur Dhaliwal stated: "The conduct of the two CNB officers facing trial... fell far short of the high standards expected of law enforcement officers and instead, has besmirched the reputation of the CNB."

The prosecutors said that the men had abetted one another, adding: "This they did by simply swopping Maung's urine sample with Hafiz's own urine, which then produced a negative Instant Urine Test (IUT) result."

They told Principal District Judge Victor Yeo that Maung and Thai national Wattansong Sakawuduean were at the CNB office at the Woodlands Checkpoint at around 11pm on Aug 15, 2018 for an IUT.

Instead of producing a sample, the court heard that Maung asked to speak with Abdul Rahman privately at around 11.50pm.

The pair then went to an interview room. Zuhairi was already there at the time.

The DPPs said: "While they were in the interview room, Maung requested for Abdul Rahman's assistance in helping him pass the IUT because he knew that his urine would test positive for methamphetamine, which he had consumed earlier.

"Meanwhile, Zuhairi left the interview room to speak to Hafiz at around 12.17am, and they agreed that they would tamper with Maung's urine sample by swopping it with another sample that would produce a negative IUT result to expedite his departure from the CNB office."

According to the prosecutors, Zuhairi entered a toilet at 12.17am on Aug 16, 2018 with a red-capped bottle which the CNB used to collect urine samples.

They added that he then left it in the toilet before walking out a minute later.

The DPPs told Judge Yeo that Hafiz later urinated into the bottle and walked out at 12.20am.

They also said: "Towards the end of the discussion between Maung and Abdul Rahman, at around 12.31am, Maung gestured at Abdul Rahman to thank him as he understood that Abdul Rahman would be assisting him in passing his IUT."

The court heard that Abdul Rahman later conducted an IUT before gesturing to his team that both Maung and Wattansong had passed the test by showing them a "thumbs up".

Officers from the Immigration and Checkpoints Authority then escorted Maung and Wattansong out of the CNB office at around 1.20am.

The offence came to light when a different CNB team detained Maung at the Woodlands Checkpoint the next day.

The DPPs said: "The conspiracy was subsequently unravelled when Maung explained that Abdul Rahman had helped him pass his previous IUT which was administered (the day before)."

CNB then referred to the matter to the Corrupt Practices Investigation Bureau. Maung's urine was later found to contain traces of methamphetamine and he was detained at a drug rehabilitation centre.

The trial involving Zuhairi and Abdul Rahman continues.

For intentionally obstructing the course of justice, an offender can be jailed for up to seven years and fined.