Mumbai, July 12: Bhaag Milkha Bhaag (Run, Milkha, Run), a biopic of the legendary Indian athlete Milkha Singh, is set for worldwide release on Friday.

The film, depicting the life and achievements of the "Flying Sikh", who overcame personal tragedy to represent India three times at the Olympics, is perhaps the most-awaited Bollywood film of the year.

Director Rakeysh Omprakash Mehra says he decided to make a film on Milkha Singh's life because it is a "fascinating" story.

As a young boy who lived in a remote village in Multan province, Milkha saw his parents and seven siblings murdered during the Partition of India and the creation of Pakistan in 1947.

As his father fell, his last words were "Bhaag Milkha Bhaag", exhorting his son to run for his life.

The boy ran - first to save his life, and then to win medals.

Arriving in India as an orphan in 1947, he took to petty crime and did odd jobs for survival until he found a place in the army. It was there that he discovered his athletic abilities.

Singh's exploits on the track and field are legendary in India - he won five golds in international athletic championships, broke a 400m record at the 1960 Rome Olympics and was awarded the Helms World Trophy in 1959 for winning 77 of his 80 international races.

Mehra, best known for his 2006 hit Rang De Basanti and Delhi-6 three years later, was chosen by Singh's golfer son, Jeev Milkha Singh, to make the biopic. The athlete sold him the rights to his story for one token rupee.

The director, who grew up with the "folklore" of the "larger-than-life" sprinter, says his film is not about Singh the athlete, but rather "the spirit of Milkha, the colours of his life".

"It's an amazing story - he was a local hero, the son of the soil, who went out and conquered the world for us."

Bhaag Milkha Bhaag, which took four years to make and cost $6.5m (£4.36m), begins in 1947 and ends in 1960.

Actor Farhan Akhtar, who plays Singh on screen, says when Mehra narrated the script to him, he "felt tremendously moved by the story".

"I was also surprised how ignorant I was about his life. We knew about him as a sporting icon, we knew he was called the Flying Sikh, but didn't know what made him the hero."

Akhtar says he trained between four and five hours a day for the role and had several meetings with Singh to learn about his running style.

"An athlete's body language is very different from an ordinary person's. And Milkha had a unique running style. Most athletes run with their arms bent at the elbows, but he ran with his arms flailing about," says Akhtar.

Singh told the BBC he used to run six hours every day.

"I would not stop till I had filled up a bucket with my sweat. I would push myself so much that in the end I would collapse and I would have to be admitted to hospital, I would pray to God to save me, promise that I would be more careful in future. And then I would do it all over again."