The XX and their record label Young Turks have revealed that the Conservative Party used the group's music without asking.
As Young Turks explains on Twitter, neither they or the Mercury Prize-winning band gave the group permission to use their music.
"Apparently David Cameron and the Tories used an XX song during their party conference," they said. "The XX/Young Turks weren't invited to any party, didn't approve the use of their music at the party and certainly don't approve of said party."
Earlier this year, Keane were "horrified" when the Conservative Party used their song 'Everybody's Changing' without permission at one of their conferences.
Last week, Labour leader Ed Miliband used songs by Vampire Weekend and Kings Of Leon at his party conference in Manchester.