Former St George Illawarra and Cronulla rugby league player Lance Thompson has died.

The 40-year-old was found dead in his unit on The Kingsway, Cronulla at about 9pm on Thursday.

The man died at the scene and the cause of his death is unknown, but police are not treating it as suspicious or an incident of self harm.

He was found by his 17-year-old daughter, Ten News reports.

Tributes flowed on social media on Friday morning for the former second rower.

Australian Rugby League Commission chair Peter Beattie said Thompson’s death was a great loss to the sport.

“A very sad day for rugby league with the passing of NRL star Lance Thompson,” Beattie tweeted.

“A much-loved member of the rugby league community. Condolences to his family.”

Meanwhile, former NRL player Darryl Brohman tweeted he caught up with “Thommo” last week and passed on his thoughts to his friends and family.

Terribly sad news of Lance Thompson’s passing. Had a beer with him last Thursday. My god! RIP Thommo. Thoughts with his family and friends

— Darryl Brohman OAM (@therealbigmarn) August 23, 2018

Very sad to hear the passing of Lance Thompson overnight, one of my childhood favourites and a local hero who I looked up to and was lucky enough to get to know over the years, champion bloke and player. Rest In Peace Mate! pic.twitter.com/0K5yWQK3g7

— Keith Galloway (@kgalloway85) August 23, 2018

I am absolutely numb at the news of Lance Thompson passing away.If you watched Lance on The Fan this year,you would appreciate what a genuine & hard working man he was. Shattered for his family.He proved you dont need to have won GF's or played for your country to be a champion.

— Andrew Voss (@AndrewVossy) August 23, 2018

The sad passing of Lance Thompson at 40yrs is a sad reminder to watch out for your mates who are struggling R.I.P
Lance Thompson 😞😞

— Terry Zarsoff (@Terryzarsoff) August 23, 2018

Thompson made his NRL debut as a 17-year-old for the Dragons in 1995, staying with the club through its merger and 1999 grand final defeat to the Melbourne Storm.

He played 38 games for the Sharks after moving to Cronulla in 2006 before he retired in 2008.

Lifeline 13 11 14

beyondblue 1300 22 4636

-with AAP