A 24-year-old Melbourne man on death row for drug trafficking in Singapore may be thrown a lifeline.

It has been revealed Nguyen Tuong Van has been providing the Australian Federal Police with information over an Australian-based international drugs syndicate.

His lawyers are hoping his assistance will improve his appeal for clemency, as Singapore's constitution states a pardon is possible if a co-accused gives evidence which leads to the conviction or arrest of a principal offender.

Nguyen's lawyer Lex Lasry has told the ABC'S AM program there is a glimmer of hope.

"It's important because the Singapore constitution itself recognises that people who assist authorities with this kind of information are deserving of particular treatments and it's significant that he's supported as he is by the Australian Federal Police," he said.

The Archbishop of Sydney, George Pell, has appealed to Pope John Paul II to help Nguyen.

Cardinal Pell says he has sent the file to the Pope in the hope he can intervene and advance the appeal for clemency.

Cardinal Pell told AM that clemency should be granted to Nguyen for a number of reasons.

"It was a very amateur attempt to smuggle 400 grams of heroin, also significantly he's more than willing to cooperate with the Australian Federal Police in an endeavour to convict whoever set him up to do this job," he said.

Nguyen received an automatic death sentence last March under Singapore's tough drug laws after he was caught carrying almost 400 grams of heroin.

At his trial, Nguyen said he was smuggling the heroin in an attempt to raise money to pay off his twin brother's legal debt.

CONDEMNED heroin trafficker Nguyen Tuong Van's chances of escaping the death penalty have improved, with the Catholic Church and the Australian Federal Police joining the Federal Government in the fight to save his life.

Sydney Archbishop Cardinal George Pell confirmed that he had asked the Pope to intercede on behalf of the Melbourne sales executive.

"I have sent off the file to the Holy Father ... asking for his support," Cardinal Pell told ABC radio yesterday.

Nguyen's lawyer, Lex Lasry QC, said his client had told police everything he knew about the bosses of an international drug syndicate.

The AFP is investigating a Sydney-based international drug syndicate, and a police spokeswoman confirmed yesterday that a letter had been sent to Mr Lasry acknowledging that Nguyen had helped with their investigation. Providing such a letter was "general police practice", she said.

Nguyen's last hope is a rare pardon from Singaporean President Sellapan Rama Nathan.

The Australian Government has also become involved, with Prime Minister John Howard speaking to the Singaporean Government about Nguyen, who was arrested in transit through Singapore's Changi airport in December 2002.

The pardon is granted only when the accused provides evidence leading to the conviction of a principal offender. If a pardon were to be granted, Nguyen would still face 20 years or more in prison.

But Mr Nathan, who is visiting Australia, would not answer a question about the case. His principal private secretary, Tan Eng Beng, told The Australian the President would not comment because "it was premature to consider a pardon".

Mr Lasry said the formal bid for clemency was lodged last Friday, and he did not expect to hear the outcome for three months.

Singaporean Prime Minister Lee Hsien Loong said last month that the decision needed to go to cabinet before a recommendation could be formulated for the President.

Nguyen, a former boy scout and salesman, was acting as a courier for the drug syndicate when he was caught carrying 396g of heroin in a backpack.

He pleaded guilty immediately, saying he was carrying the drugs in an attempt to pay off the legal debts of his drug- addicted twin brother, Khoa. But he was sentenced to death and in October last year his last appeal was rejected.

He told the court he had agreed to the drug run after being told it was the best way to pay off his brother's debts.