Elon Musk told Twitter on Monday that if the social media network fails to share data on spam and false accounts, he may walk away from his $44 billion offer to buy the firm.

According to the letter from the Tesla and SpaceX CEO’s legal firm, Skadden, Arps, Slate, Meagher & Flom, Twitter was in obvious substantial breach of its duties, and Musk maintains all rights to cancel the merger agreement.

The letter to Twitter was included in a filing with the Securities and Exchange Commission by Twitter on Monday.

Musk has previously stated that he would put the transaction on hold while waiting for Facebook to give data on the percentage of false accounts it had.

He warned that the purchase was on hold and was dismissed by Twitter, which said that the data would assist him prepare for his ownership of Twitter, not to do due diligence and resume discussions.

Musk, a self-proclaimed free-speech absolutist, has questioned Twitter’s public reports regarding spam accounts accounting for less than 5% of its user base, arguing they must be at least 20%.

He stated that he needed the information in order to perform his own research of Twitter users and that he did not trust the company’s testing techniques.

Musk has stated that he has secured funding for the purchase through both equity and loans, with the help of elite investors such as Saudi Arabian billionaire Prince Alwaleed bin Talal and Sequoia Capital.

In early trade, Twitter shares were down 5.5 percent at $37.95. A request for comment from Twitter was not immediately returned.