Twitter has threatened to sue Meta just one day after it launched a new rival app.
Threads saw 30 million users sign up within 24 hours of going live.
But now Twitter boss Elon Musk has sent a letter to Meta CEO Mark Zuckerberg, via his lawyer Alex Spiro, warning of potential legal action.
The letter says: ‘Twitter has serious concerns that Meta Platforms (Meta) has engaged in systematic, willful and unlawful misappropriation of Twitter’s trade secrets and other intellectual property.’
It claims that Meta has hired ‘dozens’ of former Twitter employees and that they have access to the company’s ‘trade secrets’.
Mr Spiro also said that many of these employees have ‘improperly retained Twitter documents and electronic devices.