A man accused of strangling his ex-partner has been found dead inside his prison cell.

Blair Dalton, 35, was critically injured at Ettalong Beach. ( Facebook: Blair Dalton )

The Corrective Services Investigation Unit says 34-year-old Lance Pearce died at the Silverwater remand centre on Friday morning.

He had been charged with intent to murder by strangulation on Tuesday, after his ex-partner Blair Dalton, 35, was critically injured at Ettalong Beach.

Ms Dalton died two days later. Police say Pearce was to face court in November when charges against him were expected to be upgraded to murder.

The Corrective Services Investigation Unit said the cause of death was not yet known but is not considered suspicious.

"A 34-year-old man has died at the Metropolitan Remand and Reception Centre in Silverwater around 11.15am, Friday 29 September," the spokesperson said.

"All deaths in custody are referred to the NSW Coroner."

Ms Dalton's friends described her as "the most beautiful, kind, caring, proud person" on a GoFundMe page that has been set up to help her family.