Nguyen's friends Bronwyn Lew and Kelly Ng will see the 25-year-old Melbourne man this morning briefly with extended visits allowed from tomorrow.

Ms Lew hopes Australians will continue calling for clemency.

"Van does not deserve to die and hopefully that message will make a difference at some point, whether it's in the next few days or the next few years," she said.

There is uncertainty over who will execute Nguyen, with reports Singapore's long time hangman has been sacked for speaking to the media.

However there has been no official confirmation Changi prison is looking for a replacement.

"They called me a few days ago and said I don't have to hang Nguyen and that I don't have to work anymore," Chief executioner Darshan Singh told Reuters on Sunday.

"I think they (the prison authorities) must be mad after seeing my pictures in the newspapers," Singh said.

Australia's Sunday Telegraph said a new executioner was expected to be flown into Singapore this week to carry out the December 2 hanging of 25-year-old Nguyen Tuong Van, who was sentenced to death for carrying 400 grams (0.9 lb) of heroin while in transit at the island-nation's airport.

Singh, a 74-year-old ethnic Indian, was reported in the Australian media to have conducted more than 850 hangings in his 50-year career. The reports said Singh had wanted to retire, but the search for a replacement was unsuccessful.

Singapore's prison department could not be reached for comment.

Despite repeated pleas from Australia to reconsider clemency for the former salesman, Singapore has stood firm on its decision, saying that Nguyen was caught with enough heroin "for 26,000 doses" and that the government would not allow Singapore to be used as a transit for illicit drugs.

Australian Prime Minister John Howard has warned Singapore to prepare for lingering resentment in Australia if it goes ahead with the execution of Nguyen, but Howard has rejected public calls in Australia for boycotts of Singaporean companies and trade sanctions with one of its closest Asian allies.

Howard made another personal appeal to Singapore's Prime Minister Lee Hsien Loong at the Commonwealth Heads of Government Meeting (CHOGM) in Malta on Saturday, Australian media reported on Sunday.

"I did have quite a discussion with him and he was left in no doubt as to the intensity of feeling within Australia," Howard told reporters. "There will be lingering resentment on the part of many Australians regarding this issue.

"They (Singapore) are certainly carefully monitoring what is occurring, but I am equally of the view, as I have been now for some time, that the government of Singapore is not going to change its mind."

New Zealand Prime Minister Helen Clark also raised Nguyen's case during informal talks in Malta, media reported.

Singapore has one of the world's toughest drug laws. Laws enacted in 1975 stipulate death by hanging for anyone aged 18 or over convicted of carrying more than 15 grams (0.5 ounce) of heroin, 30 grams (1.1 ounce) of cocaine, 500 grams (17.6 ounces) of cannabis or 250 grams (8.8 ounces) of methamphetamines.

Amnesty International said in a 2004 report that about 420 people had been hanged in Singapore since 1991, mostly for drug trafficking, giving the city-state of 4.2 million people the highest execution rate in the world relative to population.

(Additional reporting by Michael Perry in Sydney)