Kneecap is being investigated by UK counter-terrorism police following videos allegedly showing the band calling for the deaths of MPs and shouting "up Hamas, up Hezbollah".
The Belfast rap trio has had several gigs cancelled after video footage appeared to show one of them shouting "up Hamas, up Hezbollah" in November last year.
Video from November 2023 also appeared to show one member of the Irish trio saying: "The only good Tory is a dead Tory. Kill your local MP."
The group has apologised to the families of murdered MPs but claimed footage of the incident had been "exploited and weaponised", while they also said they have "never supported" Hamas or Hezbollah, which are both banned organisations in the UK.
London's Met Police said: "On April 22, we were made aware of an online video believed to be from a music event in London in November 2024.
"Following this, we were made aware of a further video, believed to be from another music event in London in November 2023.
"Both videos were referred to the Counter Terrorism Internet Referral Unit for assessment by specialist officers, who have determined there are grounds for further investigation into potential offences linked to both videos.
"The investigation is now being carried out by officers from the Met's Counter Terrorism Command and inquiries remain ongoing at this time."
In a statement posted on Instagram, the group, comprising Liam Óg Ó Hannaidh, Naoise Ó Cairealláin and JJ Ó Dochartaigh, addressed the families of Conservative MP David Amess and Labour MP Jo Cox, who were both murdered, saying "we never intended to cause you hurt", and that they "reject any suggestion that we would seek to incite violence against any MP or individual".
The manager of the group has said the band is being targeted by a "concerted campaign" designed to silence artists who speak out about the situation in Gaza.
Speaking on RTÉ's Prime Time on Tuesday, Daniel Lambert said "the last few days have been very challenging".
"At every point [the band members] have the absolute conviction that they are doing the right thing and they stand on the right side of history."
"A video didn't emerge," he said, "there was a concerted campaign emanating from the US to analyse every single thing that Kneecap has ever said."
"Why this happened was because of what they said at Coachella, and what they said at Coachella was the right thing to say. It's something we've said at Leeds, Reading, Glastonbury, in Dublin, in Belfast."
"We're in the space now of moral hysteria and moral outrage, and you’ve a band being held to higher moral account than politicians who are ignoring international law."
The daughter of David Amess said she commends the "swift action taken by law enforcement".
Katie Amess said in a statement: "Kneecap's rhetoric is not only abhorrent but poses a direct threat to the safety and well-being of elected officials and the democratic institutions they represent.
"The glorification and incitement of violence have no place in our society and must be unequivocally condemned.
"I commend the swift action taken by law enforcement agencies in addressing this and urge a thorough investigation to determine the full extent of any criminal activity.
"It is imperative that individuals and groups are held accountable for their words and actions that incite violence and hatred.
"As a society, we must stand united against all forms of extremism and ensure that our public spaces, including artistic and cultural venues, are not exploited to propagate messages of hate."
