An actors' union is calling for on-set observers to monitor all sex scenes for major Hollywood films.

The move, triggered by the Harvey Weinstein sexual harassment scandal, is part of a new code of conduct from the Screen Actors Guild-American Federation of Television and Radio Artists, which represents more than 160,000 actors in the US.

The union, SAG-AFTRA, produced a detailed seven-page guide that aims to tackle workplace sexual harassment in films, TV shows and commercials.

An actors' union has demanded on-set observes for sex scenes to tackle harassment, pictured is the infamous scene from Last Tango in Paris, in which star Maria Schneider said she felt 'a little raped'

The code of conduct defines and details what constitutes sexual harassment in the entertainment industry.

It also reveals the consequences if an employer fails to 'maintain a harassment-free workplace' and advises its members on the legal action they can take when faced with unwanted sexual situations.

The code reads: 'To end the pervasive culture of inaction and silence, we must not look the other way. We must intervene to stop the conduct when we see it, support those who speak up, and report the conduct.'

The union also unveiled a new code of conduct to stop sexual harassment during the filming of scenes for Hollywood films, TV shows and adverts (pictured are Michael Douglas and Sharon Stone in Basic Instinct in 1992)

The union intervened in 2015 when popular HBO show Westworld drew attention over a consent form given to extras in an orgy scene.

The form, from a third-party casting agency, said that the actors could be 'required to perform genital-to-genital touching'.

But after SAG-AFTRA intervened the form was revised to allow the extras to withdraw if they felt uncomfortable.

Tom Hiddleston famously exposed his bottom during a steamy sex scene with Elizabeth Debicki in TV series The Night Manager

However, others have been quick to point out the risks of sexual harassment in the industry before filming even starts.

In January, actor Emmy Rossum tweeted: 'These are sensitive situations, especially for young actors looking for a break.

'We also need to be discussing simulated sex, sexuality and nudity in our storytelling. There are guild protocols in place and contracts designed to protect actors, but we can do better.'

What could be the new rules for steamy scenes? Actors should rehearse kissing scenes by 'giving each other a peck' at first

'No use of tongues' unless the director and both actors agreed in advance

'No saliva mixing as it is abusive'

'No nudity with genitals touching (always use patches or modesty barrier)'

Producers should employ an 'intimacy director' to protect actors on set

Actors should be told in advance if they need to strip for an audition and may bring a 'support person' along Advertisement

Last month, UK-based union Equity launched its own guidelines last to tackle sexual harassment.

The actors' union, which represents 38,000 members, said it would support rules for auditions where 'people should not be asked to undress unless a mutually agreed observer is present'.

Its new guidelines will tackle simulated sex on screen and stage and could ban acts such as sharing saliva or using tongues during kisses.

According to Equity, several actresses have said they were surprised by aggressive kisses using tongues while filming, and prominent male actors and directors have been accused of abusive behaviour.

The #MeToo campaign on social media saw several actresses come forward to reveal allegations of sexually inappropriate behaviour, abuse and even rape.

Last Tango in Paris star Maria Schneider said she was not told that her co-star Marlon Brando was going to use butter as a lubricant during a scene.

Kate Winslet and Leonardo DiCaprio got very intimate during filming for the iconic 1997 film Titanic but a union now says that such scenes should be closely monitored

Bernardo Bertolucci, who directed the iconic film, said he had wanted her reaction 'as a girl, not as an actress'.

Schneider, who was 19 at the time, said she had felt humiliated and 'a little raped'.

Some actors say that 'modesty' coverings, used for sex scenes, have long been unreliable.

They have reported them as being flimsy and prone to falling off.

Fifty Shades of Grey star Jamie Dornan said 'tucking away your essentials in a little flesh-coloured bag' was a peculiar experience.