SINGAPORE - Convicted death row drug trafficker Cheong Chun Yin may yet escape the gallows, four years after being sentenced to death.

The Attorney General's Chambers (AGC) has found that he "substantively assisted" the Central Narcotics Bureau (CNB) in disrupting drug trafficking activities outside Singapore.

Last year Cheong had also claimed he provided assistance to the CNB, but was found by the AGC not to have helped enough to be given a chance at discretionary re-sentencing.

On Jan 1 last year, amendments to the Misuse of Drugs Act kicked in, giving those convicted on capital drug offences before that date an opportunity to provide assistance to the CNB to disrupt drug trafficking activities.

The AGC said on Thursday: "In light of new information received, the Public Prosecutor has now decided to certify to a court that Cheong has substantively assisted the CNB in disrupting drug trafficking activities outside Singapore."

On June 16, 2008, Cheong was arrested by CNB officers while in possession of 2,726g of diamorphine. He was sentenced to death after a trial in 2010.

His appeal against his conviction and sentence was dismissed at the time.