Hip hop Irish trio Kneecap is being investigated by UK counter-terrorism police after videos emerged allegedly showing the band calling for politicians to be killed and shouting “up Hamas, up Hezbollah.

The investigation stems from alleged videos from a Kneecap gig where the rap trio apparently shouted, “Up Hamas, up Hezbollah.” Per the BBC, both militant groups are banned in the U.K. and expressing support for them is a crime.

In an open letter organised by Heavenly Recordings, Kneecap label, artists such as Massive Attack, Paul Weller and more say that “in a democracy, no political figures or political parties should have the right to dictate who does and does not play at music festivals or gigs that will be enjoyed by thousands of people.”