The parents of James Bulger, the two-year-old boy murdered in Liverpool in 1993, have criticised the makers of a short film about the case, which has been shortlisted for an Oscar nomination.

Detainment, written and directed by Irish film-maker Vincent Lambe, is based on transcripts of the police interrogation of Robert Thompson and Jon Venables, who were 10 years old at the time and were subsequently convicted of the murder. It won best short film and special jury award in 2018 at the Young Director Award, a fringe event that takes place during the Cannes Lions festival (which in turn is separate from the high profile Cannes international film festival), and went on to win the grand prix at the Odense film festival in Denmark, which qualified it to be considered for an Academy Award.

Speaking to the Daily Mirror, Bulger’s father Ralph said that Lambe had failed to contact him. “Not once has the maker of this film contacted me or any of James’s family about this film … It has been 26 years since my son was taken and murdered and so I have seen many documentaries and news stories about him. But I have never been so cut up and offended by something that shows so little compassion to James and his family.

“I accept this is a murder of such magnitude it will always be written about and featured in the news but to make a film so ­sympathetic to James’s killers is devastating.”

Facebook Twitter Pinterest Denise Fergus, on ITV’s Loose Women. Photograph: Ken McKay/ITV/Rex/Shutterstock

Bulger’s mother, Denise Fergus, in an appearance on the ITV talk show Loose Women, also criticised the film-makers for not consulting her, and called for the Oscars to drop the film from its shortlist. “I don’t think [Lambe] had the right to do it … it’s been put on the shortlist now for the Oscar and I think it should be removed.” She also accused Lambe of exploiting the tragedy. “In my own personal opinion I think he’s just trying to big his career up. And to do that under someone else’s grief is just unbelievable and unbearable.”

Lambe had previously defended his film during an interview on Good Morning Britain after the Academy had announced its live action short film shortlist in December, when it was revealed Detainment had made it to the final nine films. Lambe, a director of commercials and music videos, said that the film “isn’t meant to bring any further anguish” to the family.

In a statement released in response to Fergus’s appearance on Loose Women, Lambe said the film “had not been made for financial gain” and apologised to her for not contacting her prior to making the film, but defended it as “in no way sympathetic to the killers and does not attempt to make excuses for them”. “There has been criticism that the film ‘humanises’ the killers, but if we cannot accept that they are human beings, we will never begin to understand what could have driven them to commit such a horrific crime. The only way to prevent something similar happening in the future is if we understand the cause of it.”

Thompson and Venables were both released in 2001 and given new identities. Venables was returned to prison in 2010 over child pornography offences; after being released in 2013, he pleaded guilty to child pornography offences in 2018, and is currently imprisoned.

The Oscar nominations will be announced on 22 January.

•This article was amended on 9 January 2019 to clarify that while it takes place during the Cannes Lions festival, the Young Director award is separately organised.