Kolkata, Oct 10 (IANS): Actor Nawazuddin Siddiqui Thursday said acting in the film "Mountain Man" was a "huge challenge", while the movie "Anwar Ka Ajab Kissa" was like an experiment for him.

Director Ketan Mehta's biopic "Mountain Man" is set in 1960 in Bihar. Based on a true story, the film is about a man named Dashrath Manjhi, who carved a path through a mountain in memory of his wife.

"(In 'Mountain Man') I play a variety of age groups..from a child to a middle-aged man to a 75-year-old in the film. This was the most tough character I have ever played in my life... it was a huge challenge," Siddiqui told mediapersons here while promoting his forthcoming films.

The film also stars Tigmanshu Dhulia, Radhika Apte and Prashant Narayanan in key roles.

For acclaimed Bengali filmmaker Budhhadeb Dasgupta's "Anwar Ka Ajab Kissa", the actor went into an experimental mode.

"I enjoyed the filming process...it was very spontaneous. It was like an experiment."

Siddiqui will be seen portraying a small time detective opposite National Award winning Bengali actress Ananya Chatterjee in the film.

"She should have been in Mumbai...I was shocked with the way she picked up the nuances of her character so well," said Siddiqui, who expressed a desire to work with all Bollywood actresses.