Tesla CEO Elon Musk says his deal to buy Twitter can't move forward unless the company shows public proof that less than 5 per cent of the accounts on the platform are fake or spam.

Musk made the comment in a reply to another user on Twitter early Tuesday.

He spent much of the previous day in a back-and-forth with Twitter CEO Parag Agrawal, who posted a series of tweets explaining his company's effort to fight bots and how it has consistently estimated that less than 5 per cent of Twitter accounts are fake.

In his tweet Tuesday, Musk said: 20 per cent fake/spam accounts, while 4 times what Twitter claims, could be much higher. My offer was based on Twitter's SEC filings being accurate.

He added that: Yesterday, Twitter's CEO publicly refused to show proof of 5 per cent. This deal cannot move forward until he does.

At a Miami technology conference Monday, Musk estimated that at least 20 per cent of Twitter's 229 million accounts are spam bots, a percentage he said was at the low end of his assessment, according to a Bloomberg News report.

Also at the All In Summit, Musk gave the strongest hint yet that he would like to pay less for Twitter than his USD 44 billion offer made last month.

He said a viable deal at a lower price would not be out of the question, according to the report by Bloomberg, which said it viewed a livestream video of the conference posted by a Twitter user.