Bollywood star Irrfan Khan, known internationally for his roles in blockbusters "Life of Pi" and "Slumdog Millionaire", shocked fans Friday by revealing he has a rare tumour.

In a statement addressing speculation by fans and the media over his health, Khan said he has been diagnosed with a neuroendocrine tumour.

The disease affects the body's hormonal messaging system and studies suggest it afflicts just 35 in 100,000 people.

"Learning that I have been diagnosed with neuroendocrine tumour as of now has admittedly been difficult, but the love and strength of those around me and that I found within me has brought me to a place of hope," Khan said on Twitter.

"To those who waited for my words, I hope to be back with more stories to tell," he said, adding that he would leave India for treatment.

Referring to rumours about his illness, Khan said a neuroendocrine tumour "is not always about the brain and googling is the easiest way to do research".

The 51-year-old Indian actor, who was in the 2016 film "Inferno" alongside Tom Hanks, is one of Bollywood's most globally-recognised exports, with a stellar career at home and in Hollywood.

He had been scheduled to start work on a film by Bollywood director Vishal Bharadwaj, who recently announced the production had been postponed due to Khan's illness.