Versatile actor Nawazuddin Siddiqui may have done challenging roles, but says his most difficult role has been in "Mountain Man", a biopic on the life of Dashrath Manjhi from Bihar.

If he won international acclaim for his work in "Gangs of Wasseypur" and "Miss Lovely", Nawazuddin was equally appreciated back home for his work in thriller "Kahaani".

"Mountain Man" is being directed by Ketan Mehta and Nawazuddin told IANS: "My role in 'Mountain Man' is one of my toughest roles that I have played so far. It's not easy at all. It's a journey of a man Dashrath Manjhi. It's a very interesting film, which also has a wonderful love story."

Dashrath Manjhi from Nagar village, in Gaya district, made impossible possible with his sheer determination and perseverance. He cut a 300-metre-long and 25-ft-wide road through a mountain to link Ghivra Mauja of Dashrath Nagar, in Gehlaur Ghati to Atara Prakhand, Wajirganj, reducing the distance from 75 km to just one km. It took him 22 years to do it.

Manjhi, fondly called Mountain Man, died in 2007. He was 70.

The actor says he recently finished the shooting of the film in Bihar.

"I have just finished the shooting of Ketan Mehta's 'Mountain Man'. It was completely shot in Bihar in a 40-day schedule. I consider myself fortunate enough to be part of the film," said Nawazuddin.

The film also stars Radhika Apte as Manjhi's wife, Falguni Devi.