Twitter has threatened to sue Meta over its new Threads platform in a letter sent to the Facebook parent’s CEO Mark Zuckerberg.

Twitter’s lawyer Alex Spiro in his letter, accused Meta of hiring former Twitter employees who “had and continue to have access to Twitter’s trade secrets and other highly confidential information,” News website Semafor has reported.

“Twitter intends to strictly enforce its intellectual property rights, and demands that Meta take immediate steps to stop using any Twitter trade secrets or other highly confidential information,” Spiro wrote in the letter.

“No one on the Threads engineering team is a former Twitter employee — that’s just not a thing,” Meta spokesperson Andy Stone said in a Threads post.

Meta, which launched Threads on Thursday and has logged more than 30 million sign ups, looks to take on Elon Musk’s Twitter by leveraging Instagram’s billions of users.