Sunny Pawar, the eight-year-old Indian star of the upcoming Australian film Lion, has been denied a visa to enter the US for the film's promotional campaign.

The young actor, due to attend premieres in Los Angeles this Friday and New York next week with his father, was unable to obtain a travel visa from the US Consulate in Mumbai because of "immigration concerns", the film's distributor The Weinstein Company said.

Lion, an Australian/British co-production supported by Screen Australia, stars Nicole Kidman and David Wenham as a Tasmanian couple who adopt young street kid Saroo (Pawar) from an orphanage in Kolkata.

Twenty-five years later, Saroo – played in his older age by Slumdog Millionaire's Dev Patel, sporting a startlingly on-point Australian accent – uses Google Earth and Facebook to track down his biological family.

Helmed by local TV director Garth Davis (Top Of The Lake) and penned by Candy author Luke Davies, it's based on the autobiographical novel A Long Way Home by the Hobart-based businessman Saroo Brierley.

Published in 2012, the film rights for Brierley's story sold for $US12 million at Cannes in 2014. He was also the subject of an episode of 60 Minutes in 2013.

According to Variety, The Weinstein Company has been angling Pawar for a potential Best Actor Oscar nomination, following strong reviews of his performance at the Toronto and London film festivals earlier this year.

"We are devastated that Sunny, an 8-year-old boy who is part of this amazing film and who is garnering such strong reactions from his performance, cannot be here to be a part of this experience," The Weinstein Company's president David Glasser said in a statement.

"We are doing everything we can to fight this; we believe it must be the effect of immigration paranoia. He, of course, poses absolutely no threat to anyone."

Lion opens in cinemas on January 19.