A leading playwright has accused the BBC of an “extraordinary” act of censorship after the corporation told her to cut key lines from a drama about “honour killings” which will be broadcast by Radio 4 this week.

Gurpreet Kaur Bhatti, whose controversial play Behzti was pulled from a Birmingham theatre in 2004 following protests from the Sikh community, wrote an episode for Radio 4’s DCI Stone series, which will be broadcast in the Afternoon Drama slot.

Bhatti’s episode, called Heart Of Darkness and due to air on Friday, tells the story of an investigation into the killing of a 16 year-old Asian girl, whose dumped body is found after being stabbed to death.

Download the new Independent Premium app Sharing the full story, not just the headlines

When it emerges that the girl was a victim of an “honour killing”, DCI Stone is told by his bosses is to treat the case “sensitively” because of her Muslim heritage.

“A week before recording I got an email from the producer saying the BBC compliance department had asked them to take lines out,” Bhatti told the Index On Censorship conference on artistic freedom of expression in the UK, held at the South Bank.

“At the end, a character says: ‘There is so much pressure in our community, to look right and to behave right.’ The compliance department came back and said ‘we don’t want to suggest the entire Muslim community condones honour killings.’

“It’s an extraordinary and awful situation. They said the lines were offensive but they absolutely were not. We live in a fear-ridden culture.

“Unbelievably, what the compliance department said was if you can find a factual example of community pressure leading to an honour killing, you can have the line. But it’s a drama, a story.

“It’s a crucial part of that story. I was very disappointed given my previous experience of censorship. If you take out the line, the whole thing changes, it’s a betrayal of the character and the truth of the unfolding story.”

Bhatti’s play Behzti, which contained scenes of rape, abuse and murder inside a Sikh temple, provoked massive demonstrations outside the Birmingham Rep. But she is now a writer on The Archers and said that Heart Of Darkness, commissioned for an afternoon slot, contained nothing that ought to be seen as provocative.

A Radio 4 spokesman said: “This is a hard-hitting drama about the realities of honour killing in Britain. A single line in the script could be taken to infer that the pressure and motivation to commit such a crime in a family comes from the wider Muslim community, potentially misrepresenting majority British Muslim attitudes to honour killing. Gurpreet Kaur Bhatti was asked to amend this line in the normal editorial process of script development.”

Sir Nicolas Serota, director of the Tate, told the conference that there was no “easy path” to free expression in the arts. “In pushing against boundaries, artists help us to question the values of our society...art is a vital space where those values can be discussed,” he said.

Sir Nicolas defended the Tate’s decision to withdraw from display God is Great, 1991, a work by John Latham featuring copies of the Bible, a Koran and a Talmud, which have been physically manipulated, in 2005.

The Tate was advised by Muslim community leaders showing the work, shortly after the July 7 bombings, could provoke protests.

However the leading lawyer Anthony Julius, of Mishcon De Reya, said: “The decision was wrong. There was no possible risk to the public or the work by showing the Latham piece. It’s possible to tell yourself horror stories of worst possible scenarios. Really brave work is being shut down because of the craven, despicable phrase ‘we can’t guarantee the safety of...’”

Sir Hugh Orde, president of the Association of Chief Police Officers, told the conference that police “tried to keep as far away as possible” from debates over the boundaries of artistic offence. Officers would make only make recommendations to remove a work, or close a play, if they had received intelligence of a genuine “threat to public order.”

Jude Kelly, Artistic Director of the Southbank Centre, warned that arts institutions could become victims of “self-censorship”, as the threat of funding cuts makes bodies avoid presenting works which might provoke a public backlash.

Ms Kelly said that the arts sector and the police were not always clear about the legal frameworks in place to protect free expression. “There are examples of when police intervened because they anticipated a public order issue,” she said.

Using examples of works by artist William Hogarth and sculptor Jacob Epstein – both of whose work was criticised by contemporaries – Sir Nicolas Serota concluded: “Things that shock and offend change with the mores of the time.”

Censorship of the arts:

Spiritual America

Spiritual America, Richard Prince’s image of a naked, heavily made-up Brooke Shields, age 10, was removed from Tate Modern’s 2009 Pop Life Exhibition following a visit from the Met. Nicolas Serota said: “The image was taken with her consent, it was freely available in books and the work was shown in New York. But the police said it could be viewed as an incitement so we removed it. There was also a threat to the security of the work.” Mr Serota argued that UK laws designed to protect young children should not have the unintended consequences of censoring works of art.

1 Day

West Midlands Police frustrated writer-director Penny Woolcock’s hard-hitting film about gang-wars in Birmingham’s Afro-Caribbean community, using street casting. “Police completely destroyed the distribution of the film. They told cinema managers there would be violence if they showed it. When I made a follow-up documentary I was followed by a patrol car. They tried to seize my rushes. They took me to court and I won with the help of Channel 4 barristers. My films gave a voice to young black men. When you transgress unspoken rules you get the full force of the State trying to stop you.”

Palestinian Embassy

Created by Norwegian performance-art duo Goksøyr & Martens and shown in Oslo, Palestinian Embassy involves a hot-air balloon in the colours of the Palestinian flag flying over the city, bearing Arabic writing and with politicians and academics on board “for diplomatic discussions on topics concerning Palestine”. Police intervened when it was repeated at the 2012 Liverpool Biennial. Sally Tallant, Biennial director, said: “There was anxiety about local political groups being antagonistic and protecting the artwork. People thought we were building a real Palestinian Embassy. There is a lack of understanding of the role of art as a space for experimentation. It’s a fear-driven environment.”

Bhezti (Dishonour)/ Behud (Beyond Belief)

Sikh playwright Gurpreet Kaur Bhatti was forced to go into hiding following the violent protests in Birmingham provoked by Bhezti (2004), which depicted a rape in a gurdwara (temple). Bhatti ran into further problems with Behud, her 2010 fictionalised response to the Behzti furore, staged in Coventry and London. “At the first dress rehearsal, West Midlands Police came and told me to pull the play because they feared that there would be a threat to public safety. They feared there would be riots but none if it materialised.” Bhatti revealed that her latest Radio 4 play has been censored by the BBC.