Famed Marvel superhero creator Stan Lee is seeking more than $1bn (£740m) in damages from his former company POW! Entertainment, alleging that he was tricked into signing a document giving away rights to use his name and likeness.

The comic-book legend, who is 95, is suing POW!, its co-founder Gill Champion and CEO Shane Duffy, alleging they brokered a “sham deal” to sell POW! to a China-based company, Camsing. Duffy is also the vice president of Camsing Entertainment.

The lawsuit also claims Champion and Duffy “conspired ... to fraudulently steal Lee’s “identity, name, image and likeness as part of a nefarious scheme to benefit financially at [his] expense”.

The claim states that since 2015 Lee has been suffering from advanced macular degeneration, meaning he has been unable to read or drive on his own. The deal with Camsing went through when Lee’s wife of almost 70 years, Joan Lee, was dying, say his lawyers, and the comics writer was “in a state of total devastation”.

“Duffy and Champion were incentivised to get a deal between POW! and Camsing done because each of them would benefit financially,” claims the suit, and that the pair “never disclosed the actual terms of the deal to Lee before closing it”.

Lee, it is argued, would not have knowingly signed a document providing the exclusive right to use his identity. “Lee did not even grant an exclusive licence to his identity, image, name and likeness to the Walt Disney Company in a multibillion dollar deal, let alone give his name and likeness away for free to a company in China,” says the lawsuit, going on to allege that his signature on a document doing so was either forged, or that he was tricked into signing it, believing it to be another document.

The lawsuit, filed in California, also says that POW! took control of Lee’s personal social media accounts, including Facebook, Instagram and Twitter.

On 13 May, Lee’s Twitter account bore the message: “Today was the first day I ever did a tweet myself. Before today, my account was done by others. I still do not have control of my Facebook. Someone else is doing it, NOT me.” On Tuesday, he posted a video to fans thanking them for their support, and tweeted: “Help! Someone has hijacked my Facebook and Instagram. I want everyone to know whoever is writing them is a fraud and is impersonating me. How do I get them back? Can you guys help?”

The suit comes one month after Lee posted an emotional video online in response to allegations that he was the victim of elder abuse at the hands of his daughter, JC Lee. In April, the Hollywood Reporter published a notarised document dated 13 February 2018 and purportedly signed by Lee, that contained claims his daughter had been verbally abusive to him. In a video, Lee called the document’s contents “totally incorrect, inaccurate, misleading and insulting”, but his then-attorney Tom Lallas alleged he had gone through the document with Lee “word by word, line by line”.

In a statement to the Guardian, POW! Entertainment said: “We have seen the copy of Mr Lee’s complaint posted on Deadline Hollywood. The allegations are completely without merit. In particular, the notion that Mr Lee did not knowingly grant POW! exclusive rights to his creative works or his identity is so preposterous that we have to wonder whether Mr Lee is personally behind this lawsuit. There is no question Mr Lee – who, along with his daughter, was and remains a substantial POW! shareholder – clearly understood the terms of the agreements he signed. The evidence, which includes Mr Lee’s subsequent statements and conduct, is overwhelming and we look forward to presenting it in court.”