It's Musk's latest salvo over inauthentic accounts, a problem he has said he wants to rid Twitter of.
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.
The battle over spam accounts kicked off last week when Musk tweeted that the Twitter deal was on on hold pending confirmation of the company's estimates that they make up less than 5 per cent of total users.
Also at the All In Summit, Musk gave the strongest hint yet that he would like to pay less for Twitter than the US$44 billion offer he 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.
Musk's comments are likely to bolster theories from analysts that the billionaire either wants out of the deal or to buy the company at a cheaper price. His tweet came in reply to one from a Tesla news site speculating that Musk "may be looking for a better Twitter deal as US$44 billion seems too high."
Musk made the offer to buy Twitter for US$54.20 per share on April 14. Twitter shares have slid since then and are now down by just over 8%, to close at US$37.39 on Monday.
To finance the acquisition, he has pledged some of his Tesla shares, but they have slumped by a third since the deal was announced.