Activists hold placards in protest at the impending execution of Nagaenthran K. Dharmalingam, sentenced to death for trafficking heroin into Singapore but diagnosed as intellectually disabled, in Kuala Lumpur, Malaysia. They said the execution of Nagaenthran would be a violation not only of international treaties but also of the Singapore constitution. Photo: AFP

A group of UN human rights experts have appealed to Singapore to halt an execution scheduled this week of a Malaysian who smuggled drugs into the city-state, on the grounds that he has intellectual disabilities.

Nagaenthran Dharmalingam, 33, is scheduled to be hanged on Wednesday, but the court stayed his execution pending an appeal to be heard on Tuesday.

The court had earlier dismissed an argument that hanging Nagaenthran would violate Singapore's constitution because he was intellectually challenged. 

"We are seriously concerned that, if the appeal is dismissed, he could still be executed imminently," the experts said in a statement.

The independent UN experts called on Singapore, which has some of the world's toughest laws on drugs, to commute the death sentence against Nagaenthran, in line with international human rights law.

Nagaenthran was detained in April 2009 for trafficking about 42.72 grams of diamorphine, or pure heroin, which was strapped to his thigh.

His lawyer M Ravi, and activists say his intellect was at a level recognized as a mental disability, and he has other disorders affecting his decision-making and impulse control.

Authorities previously said Singapore courts were satisfied Nagaenthran knew what he was doing.

The case has attracted international attention including from British billionaire and capital punishment opponent Richard Branson, who called on Singapore to spare Nagaenthran.

Reuters