SINGAPORE - A death row inmate - one of 13 who have filed a civil case that is pending before the court - appeared to have been "singled out" by a decision to schedule him for execution on April 29.

The Court of Appeal said this in written grounds issued on Monday (May 30) to explain why it upheld a stay of execution for Malaysian drug trafficker Datchinamurthy Kataiah a day before he was scheduled to be hanged.

Datchinamurthy, 36, and 12 other inmates on death row have a pending civil claim against the Attorney-General over the unauthorised disclosure of their personal letters.

Representing himself in court, he sought a judicial review in relation to the scheduling of his execution, which he argued resulted in him being treated differently from the other 12 inmates.

On the morning of April 28, High Court Judge Hoo Sheau Peng ordered a stay of execution pending the resolution of his judicial review application.

The stay was upheld that afternoon after a three-judge apex court heard and dismissed an appeal by the Attorney-General's Chambers (AGC).

On Monday, in its written grounds, the apex court said Datchinamurthy has shown that the civil case is a relevant pending proceeding in which his involvement is required.

"It was clear that (Datchinamurthy) would not have a reasonable opportunity to present his case... if the scheduled execution was proceeded with," said the grounds delivered by Justice Andrew Phang.

The Court of Appeal also agreed that Datchinamurthy has shown a case of unequal treatment, until proven otherwise.

The apex court said: "The judge did not err in her observation that although it could be that the differential treatment was reasonable in that it was based on legitimate reasons, it appeared at the present stage that the respondent had been 'singled out' by the decision to schedule him for execution on April 29, 2022."

However, the court added that this did not mean that a prisoner awaiting capital punishment would automatically be granted a stay of execution on the basis of unequal treatment.

"Every application is fact-centric, and whether a prisoner has a relevant pending proceeding would ultimately depend on the precise facts and circumstances concerned," said the court.

It made a distinction between the unusual context of the current case and unmeritorious stop-gap actions to delay an execution, such as the high-profile case of Malaysian drug trafficker Nagaenthran K. Dharmalingam.

Nagaenthran's last-minute attempt to halt his execution, originally scheduled on Nov 10, 2021, gained international prominence.

But the court said his lawyers' claim of a decline in his mental condition was baseless. He was hanged on April 27.

Datchinamurthy was convicted in 2015 of trafficking in not less than 44.96g of heroin and given the death penalty. His appeal was dismissed in 2016.

In 2020, he and fellow inmate Gobi Avedian sought to stay their executions, pending investigations into allegations of "unlawful" hanging methods.

Datchinamurthy also complained that his and Gobi's private letters were being "illegally copied and forwarded" by the Singapore Prison Service (SPS) to the AGC.

The Court of Appeal dismissed the duo's case but ruled that the SPS is not allowed to forward copies of inmates' documents without their consent or a court order.

Datchinamurthy and 12 other inmates who had their letters forwarded then pursued a civil claim, seeking damages and other reliefs.

A pre-trial conference for his judicial review application is fixed on June 1, while a pre-trial conference for the civil claim is fixed on June 9.