Madonna’s high profile performance at the Eurovision Song Contest has been shrouded in doubt amid calls to boycott the event.

The event, which is controversially taking place in Israel after calls for a cultural boycott amid the Palestine conflict, is scheduled to be held on May 18th with Madonna being lined up as the headline act.

However, Eurovision’s executive supervisor Jon Ola Sand has thrown the plans into doubt when he said: “The European Broadcasting Union has never confirmed Madonna as an act,” in a statement on Monday.

“If we do not have a signed contract she cannot perform on our stage.”

He added: “We are in a situation now that is a bit strange.”

Only a matter of weeks ago Roger Waters turned his attention to Madonna as he continues to urge artists to join his cultural boycott. Waters, who has already come to blows with Nick Cave and Radiohead’s Thom Yorke with his opinion, has asked Madonna to boycott her scheduled performance at the upcoming Eurovision Song Contest in Tel Aviv.

Writing an op-ed in the Guardian, Waters says that Madonna’s planned performance “raises, yet again, fundamentally important ethical and political questions for each and every one of us to contemplate.”

In his article, Waters also adds that the decision to host the content in Israel is “betrayal of our joint humanity.”

“Some of my fellow musicians who have recently performed in Israel say they are doing it to build bridges and further the cause of peace,” he says. “Bullshit. To perform in Israel is a lucrative gig but to do so serves to normalise the occupation, the apartheid, the ethnic cleansing, the incarceration of children, the slaughter of unarmed protesters… all that bad stuff.”

Madonna was thought to be scheduled to perform a track from her upcoming album Madame X and one more iconic song from her back catalogue, many speculation that ‘Like A Prayer’ would be chosen.

Sand continued: “We are negotiating now, in the final stage of that – but if there is no signed contract this week, she will not be on the stage.”

He Added: “We have an artist who would like to participate in the Eurovision Song Contest, and who we would love to welcome on that stage. But for that we need to have the framework secured.”