En Masse vice president of publishing Chris Lee has responded to the NCsoft accusations on the company's official forum.
"We are disappointed that NCsoft is attempting to mar the launch of Tera," he said. "Unfortunately we can't discuss much publicly due to the sensitivity of legal actions, but we do outright reject the NCsoft claims, and we are going to do everything in our power to defend and protect ourselves."
NCsoft has filed a trade secrets and unfair competition lawsuit against rival MMO developer Bluehole Studios over a US version of its game TERA, alleging it was developed using stolen assets.
Bluehole was founded by former NCsoft employees. Its US subsidiary, En Masse Entertainment, planned to launch an English language version of TERA in May, but NCsoft has argued the game is based on stolen property.
"These individuals did not leave NCsoft empty-handed or with benign intent," the complaint from NCsoft alleged of the former employees, according to MMOCulture.
"To the contrary, they made off with copious amounts of confidential and proprietary NCsoft information, computer software, hardware and artwork relating to Lineage 3."
"Their business plan was simple and audacious: create a competing product using the very work they had done while at NCsoft, launch it themselves to great fanfare and acclaim, and, in the process, deal a crippling blow to their former employer."
NCsoft seeks damages, and to stop the release of the US version of the game. En Masse Entertainment has so far only responded through its official forum, and then only to say it would not comment on legal matters.
TERA actually launched in Korea last year, even though NCsoft won a similar legal battle there, which saw the former employees convicted of stealing trade secrets. A civil case in which NCsoft was awarded damages from Bluehole was later overturned.