British writer/artist John Savage claims Gervais' Flanimals, an animated series about imaginary animals, is based on his own Captain Pottie's Wildlife Encyclopedia.
Savage, whose book was published in 2000 - four years before Flanimals, is suing the star for infringing on his artistic and literary copyright.
Savage tells the BBC: "The next stage is the High Court will be sent a copy of the writ to Mr. Gervais' lawyers and they have two weeks to decide whether to defend or accede to my request."
A spokesperson for the comedian has denied the allegations, insisting, "This story goes back several years, when John Savage first made contact with Ricky Gervais' representatives.
"At the time it was made clear that the concept and illustrations of Flanimals pre-existed John Savage's work.
"To date Ricky Gervais has not received any formal court proceedings from Mr Savage."
Gervais' Flanimals has been a best-seller, spawning three sequels. It is currently being adapted into a Hollywood movie, due for release next year (11).