The Department of Foreign Affairs says he died of self inflicted injuries.

The body of 41-year-old Emil Chang was found in a cell at Bangkok's Klong Prem prison.

Chang was arrested earlier this month after Australian authorities asked for help in his arrest and extradition.

He was due to be sent back to Sydney to face charges over a murder three years ago and with engaging in drug dealing.

At a media conference after his arrest, Chang strongly denied the charges.

He told reporters he was innocent.

Bangkok Police say he had a Thai wife and child and had been travelling in and out of Thailand for the past three years.

An autopsy to confirm the cause of death has been carried out, but the results will not be made public until next week.

AN Australian man charged with the acid-induced murder of a Sydney accountant has been found dead in a Thai prison.

Emil Chang, 41, died at Bangkok's Klong Prem prison on June 20, a Department of Foreign Affairs (DFAT) spokeswoman said today.

A post-mortem examination was under way but it was reported Chang's injuries were self-inflicted.

The results of the post-mortem would be known within a week.

Chang was arrested in Thailand earlier this month and charged with the murder of Dominic Li in January 2003.

Mr Li died after he was attacked by two men posing as postal couriers carrying a parcel bearing his name, police said at the time.

He was forced at gunpoint to swallow hydrochloric acid, which slowly burnt his oesophagus, blinded him in the left eye and eventually blocked his breathing.

Tipped off by Australian police, Thai authorities arrested Chang on June 10.

Police said then he would be sent back to Sydney within a week.

Chang, a NSW resident, strongly proclaimed his innocence at a Bangkok press conference.

"I'm innocent ... I'm a Buddhist and I don't even drink alcohol," he told reporters.

The DFAT spokeswoman said Chang's wife had been told.