More than 100 acts have pulled out of the Great Escape music festival in Brighton as part of a Palestine-related campaign against the event sponsor Barclays that has been supported by Massive Attack, Idles and Brian Eno.

The festival’s opening showcase and a keynote speech have been scrapped after performers joined Bands Boycott Barclays, a campaign that claims Barclays Bank – which sponsors several UK festivals including the Great Escape, Latitude and Isle of Wight – has increased its investment in arms companies that trade with Israel.

The annual event has become a key part of the UK’s music calendar since its launch in 2006, with about 500 artists performing in various locations around Brighton. This year about 25% of the booked performers have backed out in support of the campaign.

Jarvis Cocker was due to give a keynote speech called Biophobia, described as “a special climate-themed talk about getting to grips with nature”, hosted by Eno’s charity EarthPercent, but the event is no longer listed on the Great Escape’s website.

Anna Calvi, Stormzy and Kae Tempest have all launched their careers at the event, but this year it has become a lightning rod for divisions over the Israel-Gaza conflict.

Nick Cave, who has previously called cultural boycotts of Israel “cowardly and shameful”, was asked by a musician who was considering boycotting whether they should play or not. He responded simply by saying they should “play”, via his Red Hand Files newsletter.

Massive Attack, Idles and Eno were among dozens of artists who were not booked to play at the Great Escape festival but signed an open letter launched in April calling for it to drop Barclays as a partner.

Massive Attack’s statement said: “It’s extraordinary to think that in 2024 promoters and festivals still don’t understand that as artists, our music is for sale but our humanity and morality is not.”

In the last week dozens more artists have joined the boycott, with 120 acts backing out of performing.

Alfie Templeman, one of the most established artists due to play at this year’s event, confirmed he would not perform and said his “morals cannot and will not align with the amalgamation of entertainment and human suffering”.

A spokesperson for Bands Boycott Barclays said: “Barclays is bankrolling the genocide against Palestinians in Gaza and then laundering its reputation by partnering with music festivals like the Great Escape. As musicians, we think that’s despicable.”

The Palestine Solidarity Campaign has previously called for a boycott of the bank because it claims Barclays holds “substantial financial ties” with arms companies supplying weapons to Israel. In March the campaign group protested outside about 50 branches of the bank around the UK.

Barclays declined to comment but flagged a question and answer session during the company’s annual general meeting where it addressed the criticism of its relationship with Israeli arms firms, saying: “Barclays is not a ‘shareholder’ or ‘investor’ … in relation to these companies”. It added: “We trade in shares of listed companies in response to client instruction or demand and that may result in us holding shares.”

The festival will start on Wednesday and run for four days. The Great Escape organisers have been contacted for comment.