Prisoner Charged With Murder After Cellmate Found Dead In Sydney Jail

A prisoner accused of killing his cellmate in a western Sydney jail has been charged with murder.

A 39-year-old man was found unresponsive in his cell on Monday evening at Silverwater Correctional Centre and was unable to be revived, NSW Police say.

Detectives later charged his cellmate, Matthew Terrance John Macguire, 35, with murder.

His matter was briefly mentioned at Burwood Local Court on Tuesday where no plea was entered and bail was formally refused.

Corrective Services NSW says it's too early to speculate on what led to the attack.

The management of the inmates involved and how guards responded will be reviewed, a spokeswoman said in a statement.

"Corrective Services NSW deeply regrets the death of a 39-year-old-man ... and extends its deepest sympathy to loved ones."

The union which represents prison guards says the NSW system is "full to the brim".

The perimeter fence at Silverwater jail in Sydney's west. Image: AAP

"I would like to acknowledge the seriousness of what's taken place overnight, it indicates a prison system that is under extreme pressure," Public Service Association general secretary Stewart Little told reporters on Tuesday.

"We are dealing with a terrible, terrible ice epidemic, a drug scourge and increasingly it's making our prison system a more violent place."

Prison officers are increasingly having to intervene in "extremely volatile situations," Little said, while making it clear he wasn't commenting on Monday night's incident specifically.

Shadow Minister for Corrections Guy Zangari called on NSW Minister for Corrections Anthony Roberts to "front the public" following the incident.

"The Government has lost control of corrective services in NSW," Zangari said in a statement.

"We've just seen an inmate murdered in a facility that was meant to be secure and just 24 hours ago a convicted double murderer was able to lose their tracking device and go on the run for a day."

Damien Peters, who pleaded guilty to murdering and dismembering two of his lovers in 2001, was tracked down on Monday after he went missing from Prince of Wales Hospital on Sunday afternoon.

The perimeter fence at Silverwater jail in Sydney's west. Image: AAP

Roberts said he would not comment on the two incidents while investigations were still ongoing.

"With respect to the alleged murder at Silverwater, I extend my full sympathy to the victim’s family and I acknowledge the efforts of the many staff involved in the aftermath of this tragic death," he said in a statement.

"In regards to parole, it remains a difficult part of the justice system, but a necessary one.

"Prisons everywhere are full of violent individuals, many of who seek to continue their bad behaviour while in prison. Managing them in an enormous challenge."

Maguire is due back in Burwood Local Court in June.