By Aditya Kalra and Arpan Chaturvedi

NEW DELHI (Reuters) - Digital news units of Indian billionaires Gautam Adani and Mukesh Ambani, and other outlets like the Indian Express and the Hindustan Times, have mounted a legal challenge against OpenAI's improper use of copyright content, legal papers show.

The media outlets including Adani's NDTV and Ambani's Network18 have told a New Delhi court they want to join an ongoing lawsuit against the ChatGPT creator, as they are worried their news websites are being scraped to store and reproduce their work to users of the powerful AI tool.

Reuters is first to report the case filing by the digital news publishers, which escalates an ongoing legal battle against ChatGPT in India. In the most high-profile battle, local news agency ANI was first to file a lawsuit against OpenAI last year. Global and Indian book publishers have also now joined in.

The 135-page case filing in the New Delhi court, which is not public but was reviewed by Reuters, argues OpenAI's conduct constitutes "a clear and present danger to the valuable copyrights" of Digital News Publishers Association (DNPA) members and other outlets.

It refers to OpenAI's "wilful scraping ... and adaptation of content".

Courts across the world are hearing claims by authors, news outlets and musicians who accuse technology firms of using their copyright work to train AI services and who are seeking to have content used to train the chatbot deleted.

The filing was made by the Indian Express, Hindustan Times, Adani's NDTV and the DNPA, which represents roughly 20 companies including Mukesh Ambani Network18 and players like Dainik Bhaskar. Many of these outlets have a flourishing newspaper and television news business too.

The Times of India is not taking part in the legal challenge despite being member of the DNPA.

OpenAI did not respond to a request for comment on the new allegations. It has repeatedly denied such allegations, saying its AI systems make fair use of publicly available data.

None of the Indian media companies immediately responded to Reuters request for comment.