Musk said that he would pull out of the deal if the company didn't give him information about its fake accounts.
The company plans to give Mr. Musk access to a lot of its data.
A person with knowledge of the decision said that Mr. Musk would be allowed to access the company's "firehose", the stream of billions of tweets that flow through the company's network. It's not clear whether Mr. Musk will get full or partial access.
The information would allow Mr. Musk to figure out how many accounts are fake. He won't be able to reach the conclusion that 5 percent of the active accounts are fake since the company uses a different methodology. Mr. Musk doesn't believe in the number of fake accounts on the micro-messaging service.
It might be harder for Mr. Musk to end the deal. His lawyers sent a letter to the company accusing it of stonewalling his efforts to obtain information that was essential to closing the deal. Over the last few weeks, Mr. Musk has made barbed comments about the fake accounts on the social network.
In April, Mr. Musk agreed to buy the social network. There is a $1 billion break-up fee if the deal fails. As long as the debt financing he has corralled remains intact, the agreement includes a specific performance clause that allows him to be sued and force him to complete or pay for the deal if he doesn't.
The spokesman referred to a previous statement when asked about giving Mr. Musk access to the stream.
In order to complete the transaction in accordance with the terms of the merger agreement, we will continue to share information with him. The agreement is in the best interests of all shareholders. The transaction will be closed and the merger agreement will be enforced.
Mr. Musk did not reply immediately. The Washington Post reported that he was able to use the firehose.
Data sharing is usually part of a transaction, but the parameters around it are usually negotiated before a deal is signed. When Mr. Musk agreed to buy the company, he didn't have to do any due diligence.
The New York Times reported that Mr. Musk had previously stated that he was considering starting a new social media service. Such matters are usually addressed by limiting who can see the information.
Mr. Musk said he would make sure that anyone looking at confidential data would be bound by a non-disclosure agreement. If the deal fell apart, he wouldn't give out sensitive information about the social networking site.
5 percent of the users are fake, according to the calculation. The company said it had 229 million active users.
It is likely that Mr. Musk will need a team of experts to analyze the data, as well as the computing capacity to process and store the huge amount of information, company insiders said.