John Carmack's former employer is accusing him and "others" of improperly providing "key technology" to virtual reality headset maker Oculus VR, according to a statement from ZeniMax Media provided to Polygon.

According to the statement, the company "recently sent formal notice of its legal rights to Oculus concerning its ownership of key technology used by Oculus to develop and market the Oculus Rift. ZeniMax's technology may not be licensed, transferred or sold without ZeniMax Media's approval. ZeniMax's intellectual property rights arise by reason of extensive VR research and development works done over a number of years by John Carmack while a ZeniMax employee, and others. ZeniMax provided necessary VR technology and other valuable assistance to [Oculus VR founder] Palmer Luckey and other Oculus employees in 2012 and 2013 to make the Oculus Rift a viable VR product, superior to other VR market offerings."

A source told The Wall Street Journal that the dispute's roots trace to early 2012, when Carmack allegedly contacted Oculus VR founder Palmer Luckey, who was then researching virtual reality headsets at the University of Southern California, and Palmer sent a prototype VR headset to Carmack.

ZeniMax claims that an early prototype to which Carmack contributed software served as the template for Oculus' Rift headset, which raised $2.4 million on Kickstarter in September 2012, well beyond its $250,000 goal. ZeniMax began seeking compensation around August 2012, according to the Journal's source.

"Mr. Luckey acknowledged in writing ZeniMax's legal ownership of this intellectual property."

ZeniMax is the parent company of id Software, the development studio co-founded by Carmack where games like Doom, Quake and Rage were developed.

Oculus announced that Carmack was joining the company at CTO in August 2013, when his plan was to continue working at both companies. Carmack resigned from id in November. Carmack later said that he left id Software because he couldn't work on virtual reality there.

"The proprietary technology and know-how Mr. Carmack developed when he was a ZeniMax employee, and used by Oculus, are owned by ZeniMax," the company's statement continues. "Well before the Facebook transaction was announced, Mr. Luckey acknowledged in writing ZeniMax's legal ownership of this intellectual property. It was further agreed that Mr. Luckey would not disclose this technology to third persons without approval. Oculus has used and exploited ZeniMax's technology and intellectual property without authorization, compensation or credit to ZeniMax. ZeniMax and Oculus previously attempted to reach an agreement whereby ZeniMax would be compensated for its intellectual property through equity ownership in Oculus but were unable to reach a satisfactory resolution. ZeniMax believes it is necessary to address these matters now and will take the necessary action to protect its interests."

"It was only through the concerted efforts of Mr. Carmack, using technology developed over many years at, and owned by, ZeniMax, that Mr. Luckey was able to transform his garage-based pipe dream into a working reality," the Journal reported, based on an April 18 letter from ZeniMax to Oculus' lawyers and Facebook's general counsel, Colin Stretch.

We've reached out to Oculus for comment and will update this article with more information as we receive it. Facebook declined to comment for this article.

Update: John Carmack took to Twitter this afternoon to weigh in on ZeniMax's ownership claims.