Film-maker Jason Soo has appealed to the Films Appeal Committee (FAC) for a PG13 rating for his documentary on detainees arrested in 1987 over an alleged Marxist plot.
The documentary, 1987: Untracing The Conspiracy, has been given an R21 rating by the Media Development Authority (MDA).
It features interviews with former detainees of Operation Spectrum, which saw 22 people rounded up in 1987 under the Internal Security Act over an alleged Marxist conspiracy to overthrow the Government.
The MDA, in giving the rating, had said in its advisory that "maturity will be required to understand the historical and socio-political circumstances surrounding the incident, and to discern that the film presents a perspective by the detainees".
Mr Soo said in a Facebook post on Monday that he met the FAC, an independent 15-member panel, to ask for a PG13 rating instead.
He said his film includes not just interviews with seven former detainees but also archival material such as newspaper articles.
He added that the film presents "the established narrative of Operation Spectrum as well as alternative stories of what happened".
In his appeal letter, he pointed to the extensive coverage of the operation by local newspapers in 1987, and prime-time TV programmes during the period. "If these television programmes were accessible to everyone and (were) not rated R21 in 1987, there is no reason that a R21 rating is needed now," he said.
His documentary had a one-time screening during the Freedom Film Festival here last November. It was given an R21 rating.
Mr Soo had made a fresh application for a rating last December for future screenings. The MDA in April gave it an R21 rating.