A TV One film should have carried a warning as it contained a rape scene, the Broadcasting Standards Authority (BSA) has found.

The film, The Tiger's Tail, which screened on TV One's Sunday Theatre on October 31, told the story of a successful Dublin property developer, Liam O'Leary, whose life takes a sinister twist when his estranged twin brother convinces his family that he is Liam.

About one hour into the film, the twin brother was shown standing in the doorway of Liam's bedroom watching Liam's wife Jane. Jane and Liam had previously argued, and Jane, thinking the twin was Liam, told him to "change and get out". The twin removed his jacket, tie and pants, put his arms around Jane and touched her breasts.

Jane snapped at him, "stop that!" and slapped his hands away. He continued to touch Jane and kissed her neck as she tried to fend him off. The twin kissed Jane forcefully, threw her on the bed and began raping her. After a few moments she appeared to enjoy it; she moaned, touched his face and gasped in pleasure "Oh Liam". The scene ended with the couple kissing passionately.

Complainant Rhonda Findlay said during the scene it was apparent the woman found "rape" a "pleasurable experience" and the outcome was also "positive".

She said the scene mixed consensual sex and force, was designed to titillate, glamorised rape, and failed to portray the "deep trauma and aftermath of a very serious crime against a person's body and psyche".

TVNZ declined to uphold the complaint saying The Tiger's Tail was classified AO, screened at 8.30pm and had an adult target audience. TVNZ said it was an "intricate movie with mature themes" and the central storyline was dealt with in a "challenging" but "legitimate" manner.

TVNZ said the sex scene was broadcast at 9.29pm, well into the movie, "which had by then established itself as having substantial dark and sinister overtones".

The broadcaster accepted the scene was "intentionally unsettling", but argued the violence shown was minimal and the sexual activity was presented as consensual, brief and relatively inexplicit.

Dissatisfied with TVNZ's response the complainant referred the matter to the BSA.

In its decision, the BSA noted a guideline to the violence standard in the Free-to-Air Television Code stated: "Any programme in which rape is depicted should be preceded by a warning."

The BSA said the guideline applied regardless of the programme's genre, classification or time of broadcast.

"Although guidelines do not, of themselves, impose requirements on broadcasters, we consider that this guideline is of particular importance due to the inherently distressing nature of rape. It is our view that such themes, however depicted, must be treated with the utmost sensitivity and care," the BSA said.

"The broadcaster did not exercise appropriate care and discretion when dealing with the issue of violence because it failed to precede this programme with a specific warning that rape would be depicted."

The BSA declined to uphold other aspects of the complaint.