Rugby league Immortal Graeme Langlands has died overnight in his Sutherland nursing home, after battling poor health for months.

His family released a statement on Sunday morning expressing their sadness and a desire for privacy.

"Graeme was in very poor health and suffering from a number of chronic diseases," the statement reads. "His family are relieved by the nurse's advice that his passing was peaceful and painless."

The 76-year-old had been suffering from dementia and Alzheimer's, his lawyer said, amid allegations of indecent treatment of a girl under 16 in the 1980s.

The family addressed the legal proceedings in the statement, claiming Queensland Police's "egregious prosecution" of Langlands over the past few months had only served to heighten their devastation.

"The family maintains its position that this was an improper prosecution and that the allegations are refutable on the evidence in their possession. The family reserve making further comment to a later time."

NRL chief executive Todd Greenberg led the rugby league community's condolences on Sunday morning, noting the impact the player had on the game as one of eight Immortals.

"He was such a dominant player in his era ??? so many fans would remember growing up watching 'Changa' at his best," Greenberg said. "It is a sad loss for the rugby league community and especially for those closest to him."

In his prime, Langlands had the best sidestep in the game. But his life after league was marked by an injury, estrangement from his son and a legal battle as he worked at a series of jobs, including as a bar manager in the Philippines.

He played 45 Tests for Australia, including 15 as captain, and more than 200 games for the Dragons between 1963 and 1976.

Rest in Peace, Changa.https://t.co/rH6CLUcL5k#NRL pic.twitter.com/Fn0RX36JXa??? NRL (@NRL) January 21, 2018