The Tesla chief executive made the allegations in a countersuit against the social media company, which is taking Musk to court in an attempt to make him complete an agreed $44bn (£36.5bn) takeover of the business.
Twitter has consistently stated that spam accounts represent less than 5% of its user base, which currently stands at just under 238 million.
Musk claims that Twitter has overstated the number of monetisable daily active users on the platform, or users who see ads. The number of users that see ads is 65 million lower, the lawsuit claims.
Spam accounts are automated, meaning they are not operated by a human hand, and are designed to manipulate users or disrupt their interactions on the platform.
