Bollywood star Salman Khan, second left, was convicted of poaching rare deer in a wildlife preserve two decades ago and could face up to six years in prison. Picture: Sunil Verma/AP

Rajasthan - Bollywood superstar Salman Khan was found guilty Thursday of killing endangered wildlife nearly two decades ago, a prosecutor said, a charge that could see the bad boy of Indian cinema jailed for six years.

Khan, one of the Indian movie industry's most bankable stars, was convicted by a court in Rajasthan state of poaching the rare antelopes known as black bucks in 1998.

He will be sentenced later on Thursday and faces between one and six years in prison for the crime that has gripped cinema-obsessed India for decades.

Hundreds of police were deployed outside the courtroom in Jodhpur to keep back fans who massed to support the body-building actor best known for his macho roles.

Khan, wearing black sunglasses and a figure-hugging black shirt, walked briskly from a white SUV to the courthouse flanked by security.

Four other Bollywood stars - Saif Ali Khan, Sonali Bendre, Tabu and Neelam Kothari - were also accused of joining the hunting trip but were acquitted for lack of evidence.

"Salman Khan has been convicted under the wildlife protection act and the rest of the stars have been acquitted," prosecutor Mahipal Bishnoi told reporters.

Khan, whose legion of fans emulate his distinct hairstyle and fashion, has accused the state's forest department of framing him over the black buck case.

His defence lawyers had suggested the black buck died of natural causes such as overeating, and claimed there was no evidence they had been shot.

Controversial bad boy 

The 52-year-old has been dogged by multiple charges since undertaking the infamous hunting safari in protected forest land while shooting a film in Rajasthan.

The Bishnois, a Rajasthani tribe seen as custodians of the region's wildlife, filed a complaint against the actors.

Khan was found guilty of killing gazelles on the hunting trip and served a very brief stint in jail, but was freed on appeal in 2016.

Last year he was also cleared by a court over the alleged use of unlicensed firearms on the expedition. A higher court is challenging his aquittal.

Controversy has followed the Bollywood bad boy since he burst onto the silver screen in the 1980s.

He was cleared in 2015 of killing a homeless man in a hit-and-run accident. That decision is now being challenged in the Supreme Court.

Indian courts can often take years - and sometimes decades - to pronounce verdicts.

He was also accused of assaulting a former Miss World and provoked a firestorm in 2016 by saying his workout schedule for a film left him feeling "like a raped woman".

But the off-screen drama has done little to dampen his appeal.

The actor known as "bhai", meaning "brother" in Hindi, enjoys a cult-like status with the majority of his devotees young men who envy Khan for being unmarried at 52.

He remains one of Bollywood's biggest draws, starring in more than 100 films and television shows.

According to Forbes, he made $37 million in yearly earnings to finish second behind Shah Rukh Khan in the 2017 Bollywood rankings.

Both the Khans are among the top 10 most highly paid actors in the world.

The Bollywood heartthrob's latest blockbuster "Tiger Zinda Hai" (Tiger is alive) collected some $85 million worldwide.