Bollywood star Kader Khan has died in hospital in Canada at the age of 81 following a prolonged illness.

Khan, who was renowned for his comedic roles, especially during the 1990s, had been suffering from progressive supranuclear palsy, an extremely rare degenerative brain disease, according to CNN affiliate News 18. 

Indian Prime Minister Narendra Modi was among the many who expressed sadness at Khan's passing Tuesday, describing him as a performer who "brightened the screen with his stupendous acting skills and lightened it thanks to his unique sense of humour."

Former actress turned politician Smriti Irani also paid tribute to the veteran actor, tweeting, "If you were a late 80s-90s kid who watched Hindi films, chances are you encountered the magic of Kader Khan."

Khan was born in 1937 in Kabul, Afghanistan. His family moved to Mumbai when he was a young boy.

He made his acting debut in 1973 with the film "Daag" starring Rajesh Khanna and Sharmila Tagore. Over the course of his career, he went on to act in over 300 films.

Prior to making his on screen debut, Khan was a renowned scriptwriter, whose talents helped to produce a string of Bollywood smash hits, including "Dharam Veer," "Coolie," "Amar Akbar Anthony," "Sharaabi," "Lawaaris" and "Muqaddar Ka Sikandar."

On Tuesday, Bollywood stars past and present took to social media to offer their condolences, amid a flood of heartfelt tributes.

Amitabh Bachchan described the news of Khan's death as "depressing," adding that he was a "writer of eminence in most of my very successful films."

Actor Anupam Kher said being on set with Khan was "a joy and a learning experience."