Gwen Stefani is being sued for $25 million by her former hair dresser.

Gwen Stefani

Gwen Stefani

The 37-year-old singer has been accused by Richard Morrill of stealing his lyrics for 'Spark the Fire', the 2014 song she worked on with Pharrell Williams, and he is also taking action against the producer for not "supervising Stefani" during the writing process.

In documents obtained by E! News, Richard claimed he gave Gwen a copy of his own band L.A.P.D.'s song, 'Who's Got My Lightah' in 1998 after she heard in playing while he was styling her hair.

He accused the 'Hollaback Girl' hitmaker of copying the chorus of the song he wrote for her own hit, changing the line "Who's got my lightah?" to "Who's got the lighter? Let's spark the fire", pronouncing the final word as fi-ya.

Richard insists the rhythm, melody and background music of 'Spark the Fire's chorus - which features four times in the song - is almost identical to that of 'Who's Got My Lighter' and they are sung in the same key.

And he cited a 2014 interview with Elle magazine, in which Gwen stated Pharrell had written most of the song, apart from the chorus, which she had contributed.

Richard claims the pair have made at least $25 million directly and indirectly so wants them to pay all damages due to "their unlawful acts" with prejudgment interest, as well as account for and pay all profits that they have "enjoyed at his expense."

He is also asking seeking the cost of "corrective advertising necessary due to harm to the exclusivity of the copyright and other misleading aspects of Defendants' actions."

He also wants his costs and attorneys' fees to be paid.