San Francisco, California - X unveiled a $16-a-month subscription plan allowing users who pay more to get the biggest boost for the replies they post on the platform.

The Premium+ plan is ad-free and designed to provide "the largest reply boost" on X, the company said in a post.

The plan builds on features offered in a Blue subscription plan costing $3 monthly and a Premium Plan priced at $8 monthly, according to X.

Listed features of Premium+ include a blue tick next to names in profiles along with "a visible ID verification label."

The platform recently started charging new users in New Zealand and the Philippines for basic features such as posting messages in a trial aimed at reducing spam.

Owner Elon Musk has suggested charging all users, but the idea was widely panned. Industry analysts said it would make X even less appealing to advertisers.

He started charging for features that were once free on Twitter, such as blue tick marks originally intended as badges of authenticity, in an effort to make money from subscriptions.

X is also experimenting with video and audio calling, according to a recent post by Musk.

Industry experts have blamed the billionaire for making the erstwhile Twitter worse, singling out his tinkering with the verification process as a particularly damaging move.