An Australian drug runner has been put to death in Singapore.
The execution led to mourning across Australia
Nguyen Tuong Van, 25, of Vietnamese descent, was hanged at Changi prison despite repeated pleas for clemency from the Australian government.
He was convicted three years ago of carrying nearly 400g (14 ounces) of heroin at Singapore airport while travelling from Cambodia to Australia.
Australian PM John Howard said the execution would harm links between the people of Australia and Singapore.
Australian Attorney-General Philip Ruddock had earlier condemned the execution as "barbaric".
A vigil by anti-death penalty campaigners took place outside the prison overnight.
And hundreds of supporters gathered in Nguyen's home city of Melbourne at a church to mark the moment of his execution. A large church bell rang 25 times - once for every year of his life.
At the same time, dozens of people held a silent vigil outside the Singapore High Commission in the capital Canberra.
In a statement announcing the execution just before dawn, Singapore's home affairs ministry said Nguyen had failed in his appeals for clemency to the court of appeal and to President S R Nathan.
The authorities in Singapore had earlier argued that they had an obligation to protect those whose lives could have been ruined by the heroin he was smuggling.
The amount of heroin involved would have been enough for 26,000 individual doses, they added.
Boycott call rejected
Mr Howard said: "I have told the prime minister of Singapore that I believe it will have an effect on the relationship on a people-to-people, population-to-population basis."
Nguyen had said he was trying to help his brother
The prime minister said he felt sympathy for Nguyen's mother, and had been disappointed by Singapore's "clinical response" to Australia's request that she be allowed to hug her son before his death. The Singapore authorities had only allowed them to hold hands.
But Mr Howard has rejected calls for trade and military boycotts against Singapore, one of Australia's strongest allies in Asia.
He added that the execution should serve as a warning to other young Australians.
"Don't imagine for a moment that you can risk carrying drugs anywhere in Asia without suffering the most severe consequences," he said.
The BBC's Phil Mercer in Australia says that critics have insisted that Mr Howard should have done much more to spare this young drug trafficker from the gallows.
Human rights watchdog Amnesty International condemned the execution.
Tim Goodwin, Amnesty International's anti-death penalty co-ordinator, told AFP news agency: "It is an extremely sad day for his family, who have been brutalised by this cruel punishment."
The case has prompted intense interest in Australia, though a poll released on Thursday suggested people were divided over whether the death penalty was justified.
Nguyen's mother had fought for clemency for her son
Singapore has some of the strictest drug trafficking laws in the world, and anyone found with 15g of heroin faces a mandatory death penalty.
Mr Ruddock said the case had mitigating circumstances, because Nguyen maintained he had smuggled the drugs to earn enough money to pay off legal bills of A$30,000 (£13,000) incurred by his twin brother, a former heroin addict.
One of Nguyen's lawyers, Lex Lasry, told the BBC the execution was a "mockery of justice", pointing out that his client had spent two years in a rehabilitation centre.
According to Amnesty International, about 420 people have been hanged in Singapore since 1991, mostly for drugs offences.
Nguyen was the first Australian to be executed overseas in more than a decade.