New Delhi, Apr 14 (IANS): Before deleting all legacy Blue tick marks on April 20, Twitter on Friday introduced a feature that allows posts with 10,000 characters for paid Blue subscribers.

Twitter now supports tweets up to 10,000 characters in length, "with bold and italic text formatting," the company informed.

In February, the micro-blogging platform introduced 4,000-character-long tweets for Blue subscribers.

"Sign up for Twitter Blue to access these new features, and apply to enable Subscriptions on your account to earn income directly on Twitter. Tap on 'Monetization' in settings," said the Elon Musk-run company.

Musk on Thursday announced that 'Subscriptions' are now enabled on the platform -- a way for people's most engaged followers to help them earn money from Twitter for their contributions on the platform.

"We're firing up creator subscriptions bigtime! Works for longform text, pics or video," Musk posted.

The decision to introduce 10,000-character-long tweets comes as Twitter is embroiled in a fight with popular subscription newsletter platform Substack.

Substack hit back at Twitter for blocking the ability to like or retweet any posts containing the word 'Substack', saying the whole situation is "very frustrating."

The company CEO Chris Best responded to Musk with a post on Substack Notes, saying Substack links have been obviously severely throttled on Twitter.

The Twitter move has become a huge problem for Substack writers, who use the Musk-run platform to promote their newsletters.