Actor Abhishek Bachchan, who is playing freedom fighter Surya Sen in the forthcoming period film "Khelein Hum Jee Jaan Sey", says lack of reference about Sen made it difficult for him to essay the part.

"As an actor it was difficult because there was no ready reference. While discussing someone who is a true life character, you can't be untrue or deviate too far, " said Abhishek at a press conference.

"If we just conceive a character from our imagination, it's easy to play because you can let your imagination run wild and then work within the parameters set by the director.

"Being a true life character made it slightly challenging because we didn't have much information. There is no video or film footage on Surya da. There were very little photographs of him and most of them were post his arrest, post the uprising, " she added.

Based on Manini Chatterjee's book "Do and Die: The Chittagong Uprising 1930-34", "Khelein Hum Jee Jaan Sey" is a true story of the revolution of 1930 against the British which happened in Chittagong, then a district of undivided Bengal.

The extensive research on the characters by director Ashutosh Gowariker made it easy for Abhishek.

"It became easy because Ashu (Ashutosh) was so well prepared. He is so confident about what he wants. And that makes your job much easier. He did extensive research, which he shared with everyone. Everyone had read the book, so everyone kind of knew the skeleton and the fleshing out was done by Ashutosh, " said Abhishek.

Actress Deepika Padukone plays freedom fighter Kalpana Dutt in the movie.