Bollywood superstar Shah Rukh Khan has become the latest high profile figure to speak out against "extreme intolerance" in India.

Khan, who turned 50 on Monday said, "there is intolerance, there is extreme intolerance… there is, I think… there is growing intolerance."

He said he "respected" people returning awards to protest against intolerance.

A movement that began with writers returning state awards has spread to scientists, historians and filmmakers.

They have cited the killing of rationalists MM Kalburgi and Govind Pansare, as well as the lynching of a man over suspicions he consumed beef, as examples of rising intolerance in India.

More than 50 historians have returned national and state awards, joining almost 40 writers who have done the same.

Scientists and film makers have also joined the protest, while some people in the business community have expressed concerns.

"We have made a huge thing about our meat-eating habits. How can the food habits of people be an issue?" Khan told the NDTV news channel.

"It is stupid… It is stupid to be intolerant and this is our biggest issue, not just an issue… Religious intolerance and not being secular in this country is the worst kind of crime that you can do as a patriot."

Khan's statement caused chatter on social media.

Khan's statement came one day after India's central bank governor Raghuram Rajan made a "plea for tolerance in India" saying that "tolerance means not being so insecure about one's ideas that one cannot subject them to challenge".

Two of India's top business leaders, the founder of Infosys NR Narayana Murthy, and chairman of Biocon Kiran Mazumdar Shaw have also warned that the current situation would deter investments in India.

The Indian government has dismissed the allegations.

India's Home Minister Rajnath Singh told those returning awards to "give suggestions instead of returning awards" and maintained that the incidents being cited were law and order issues that did not necessarily point to intolerance.

Lawmakers from the ruling BJP had called the beef lynching incident a "spontaneous expression of anger".

Finance minister Arun Jaitley has lashed out at "liberal intolerance" and said that the prime minister had been the worst victim of "structured and organised propaganda that there is a social strife in India".