A retired NFL player whose rags to riches story inspired faith-based movie The Blind Side is suing the Christian couple who took him in as a teenager.

According to court documents obtained by US media outlets, Michael Oher alleges financial exploitation by Sean and Leigh Anne Tuohy. 

The 37-year-old claims he was led to believe he was being adopted by the couple but was instead placed under a conservatorship that allowed them to profit off his name. 

The claims are contained in a petition filed in probate court in Shelby County, Tennessee, on Monday.

"The conservatorship to which he consented on the basis that doing so would make him a member of the Tuohy family, in fact provided him no familial relationship with the Tuohys," the filing stated, according to the Associated Press.

The story of Mr Oher being taken in by the Tuohys and going on to become a successfull NFL star formed the basis of a book called The Blind Side. 

In 2009, the book was turned into a movie starring Sandra Bullock as Leigh Anne Tuohy. The movie won Bullock a Best Actress Oscar and was a hit among Christians because of the Tuohys' Christian faith. 

The lawsuit also alleges that Mr Oher that did not make any money from the movie.

In comments to the Daily Memphian news outlet, Sean Tuohy denied the allegations and said that they did not make any money from the movie but only received a share of the profits from the book. 

"We're devastated," he said of the claims. "It's upsetting to think we would make money off any of our children. But we're going to love Michael at 37 just like we loved him at 16."