Gnarls Barkley have cancelled a sold-out show in London and scrapped all of their U.K. promotional duties because of a serious "family illness".

The Crazy hitmakers were due to play a gig at the British capital’s 229 Club on Thursday to support their newly-released album The Odd Couple, but had to pull the date after a relative of singer Cee-Lo Green fell ill.

A statement from the band reads: "Cee-Lo Green decided at short notice to remain in the States alongside his wife and children, and is thus now unable to travel to the U.K. as scheduled."