The last picture of Malaysian citizen S Prabagaran, 29, who had a photo shoot in prison prior to his execution in Singapore, has made its rounds on social media.

The photograph was uploaded by anti-death penalty NGO We Believe in Second Chances hours after he was executed.

"Prabagaran was hanged in Changi Prison (yesterday) morning.

"His family have asked that we share these photos of his final photo shoot in prison, as well as his last rites before his final journey," the NGO said in a Facebook posting.

The photograph shows Prabagaran, dressed in a kurta, smiling.

The NGO also shared other pictures, including that of Prabagaran's last rites.

"They say that he has always maintained his innocence, even though he ultimately accepted that he would be executed.

"Those who were with him said he was jovial and joking with the prison guards even as the end neared.

"The family would like to thank everyone who has supported them, from the lawyers who fought in the courts of Singapore and Malaysia, to those who were present at the vigil, and those who sent their best wishes and prayers," We Believe in Second Chances said in a statement.

Prabagaran was executed at 6am yesterday.

He was arrested at the Woodlands Checkpoint in April 2012, after he was found in possesion of 22.24g of heroin in the car he was driving.

The petrol station worker had maintained his innocence, saying he had borrowed the car from a friend.

He was sentenced to death in 2015, and had exhausted all means of legal recourse in Singapore when his lawyers filed an application to compel the Malaysian government to take his case to the International Court of Justice (ICJ).

This process was still pending at the Malaysian Court of Appeal when the execution was carried out.