Elon Musk has accused Apple of threatening to block Twitter from its app store without saying why in a series of tweets that also said the iPhone maker had stopped advertising on the social media platform.

The billionaire CEO of Twitter and Tesla said Apple was pressuring Twitter over content moderation demands.

The action, unconfirmed by Apple, would not be unusual as the company has routinely enforced its rules and previously removed apps such as Gab and Parler.

Parler, which is popular with US conservatives, was restored by Apple in 2021 after the app updated its content and moderation practices, the companies said at the time.

“Apple has mostly stopped advertising on Twitter. Do they hate free speech in America?,” Musk, who took Twitter private for US$44-billion last month, said in a tweet.

He later tagged Apple CEO Tim Cook’s Twitter account in another tweet, asking, “What’s going on here?”

Apple did not immediately respond to requests for comment.

“It wasn’t clear to me how far up the Apple food chain that idea went internally and without knowing that, it isn’t clear how seriously to take any of this,” said Randal Picker, a professor at the University of Chicago Law School.

Top advertiser

The world’s most valuable firm spent an estimated $131 600 on Twitter ads between 10 and 16 November, down from $220 800 between 16 and 22 October, the week before Musk closed the Twitter deal, according to ad measurement firm Pathmatics.

In the first quarter of 2022, Apple was the top advertiser on Twitter, spending $48-million and accounting for more than 4% of total revenue for the period, the Washington Post reported, citing an internal Twitter document.

Twitter did not immediately respond to a request for comment on the report.

Among the list of grievances tweeted by Musk was the up to 30% fee Apple charges software developers for in-app purchases, with Musk posting a meme suggesting he was willing to “go to war” with Apple rather than paying the commission.

The fee has drawn criticism and lawsuits from companies such as Epic Games, the maker of Fortnite, while attracting the scrutiny of regulators globally.

Apple has mostly stopped advertising on Twitter. Do they hate free speech in America?

— Elon Musk (@elonmusk) November 28, 2022

The commission could weigh on Musk’s attempts to boost subscription revenue at Twitter, in part to make up for the exodus of advertisers over content moderation concerns.

Companies from General Mills Inc to luxury automaker Audi of America have stopped or paused advertising on Twitter since the acquisition, and Musk said earlier this month that the company had seen a “massive” drop in revenue.

Ad sales account for about 90% of Twitter’s revenue.