Singapore activists have tried and failed to deliver a bundle of messages of support to Australian drug trafficker Nguyen Tuong Van as he sits on Singapore's death row.

Human rights lawyer M Ravi said police at Changi Prison, where Nguyen is being held with just days before his execution, had blocked the delivery on two occasions to take the letters.

"They refused to take them," said Ravi, who is not Nguyen's counsel but has crusaded in the city-state on behalf of the former Melbourne salesman.

"I am absolutely disgusted and outraged as a citizen of this country," Ravi told AAP. "It is very, very painful for us at the moment."

No comment was immediately available from the police or the prison authorities.

Nguyen, 25, was arrested at Singapore's Changi airport while in transit from Cambodia to Australia in December 2002.

He was sentenced to death in March 2004 for carrying almost 400 grams of heroin. Calls for clemency from Australia have failed to change Singapore's mind.

Meanwhile, Foreign Minister Alexander Downer plans to make a last ditch plea to save Nguyen's life when he meets his Singaporean counterpart George Yeo at the Asia-Pacific Economic Co-operation (APEC) meeting next week.

"We've put an enormous amount of effort into trying to save Van Nguyen's life, I've said all along ... that I was very pessimistic that we would be able to turn this around," he said.

Mr Yeo wrote to Mr Downer last week, rejecting the government's most recent appeal for clemency for Nguyen.

"I'll be meeting with him again next week in South Korea and will raise it with him once more when I meet him in South Korea," Mr Downer said.

The 80-or-so letters of support for Nguyen were gathered at a rare protest held at which speakers urged that his life be spared, and the city-state halt all executions.

The bundle included an emotional note from the mother of a man hanged in Singapore in May in which she described Nguyen as being "like her son".

Letchumi Murugesu said her son Shanmugam, who was executed for importing more than a kilogram of cannabis, knew Nguyen in prison.

"My son has told me about you before he died," she said in her one-page handwritten message, which also contained an outline of her hand.

"Shanmugam told me to save you, even if he is to die."

Ravi, who represented Shanmugam, said he is appealing for help from the United Nations to halt the execution.

He said he is sending an urgent note to Philip Alston, an Australian who is the UN's Geneva-based special rapporteur on extra-judicial, summary, or arbitrary executions.

By tradition Singapore executes death row inmates on Fridays at dawn.

Activists say that Nguyen is likely to die this Friday or November 18.

So far there has been no confirmation yet of a date from his family or legal team.

• Nguyen Tuong Van Case Information

THAILAND likes to parade its villains. In recent days Thai television has aired taxi-driver Narong Panyee's confession that he had robbed and raped more female passengers than he could remember since his release from prison two years ago. During the report, the news ticker began to roll across the bottom of the screen, streaming viewer anger via SMS: "He should be castrated"; "He should die"; "We should kill him".

In Thailand, 80 per cent of the population support the death penalty. If Narong is found guilty and sentenced to death - the death penalty is discretionary for rape in Thailand - he will join the 955 men and women who Amnesty International say are on death row in the country. Ninety-five have exhausted all judicial appeals and only a royal pardon can save them from death by lethal injection.

Unlike Thailand, Singapore likes to hide its "villains"; out of sight, out of mind. When friends of Shanmugam Murugesu, an eight-year army veteran and jet ski world champion, held a concert and vigil, Hanged at Dawn, to try to stop his execution, authorities banned the use of Shanmugam's face on the promotional flyers. He was hanged on Friday, May 13, for importing close to two kilograms of cannabis.

The Singapore Government will not say how many prisoners are on death row but civil society groups believe there are eight. The most recent polling showed 70 per cent of Singaporeans support the death penalty.

In recent years, Amnesty International has mapped a global trend towards abolition of the death penalty, saying in 1997 that half the countries in the world were now abolitionist in law or in practice - but noting that the trend was not reflected in South-East Asia. Only Cambodia and East Timor, whose constitutions were written with United Nations assistance, do not have the death penalty. Most governments and citizens remain in favour.

Means of execution vary: Indonesia and Vietnam use a firing squad; the Philippines uses lethal injection and Thailand moved from shooting to lethal injection in 2003; and Singapore and Malaysia employ the hangman. Vietnam is also mulling a change to lethal injection.

This week, as Australia woke up to the horror of the imminent execution of Australian Nguyen Tuong Van in South-East Asia, what is most apparent is the lack of discussion of or concern about the death penalty.

Even in Singapore, Nguyen's case has barely registered. After a brief report on his failed clemency appeal, The Straits Times ran a wire agency story, filed from Canberra, on the reaction in Australia. The story ran in the world section, as if it had nothing to do with Singapore.