Illustration shows Elon Musk photo and Twitter logo
Twitter logo and a photo of Elon Musk are displayed through magnifier in this illustration taken October 27, 2022. Reuters

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

The billionaire CEO of Twitter and Tesla also 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 that led to the removal of apps such as Gab and Parler, which is popular with U.S. conservatives.

Parler 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 $44 billion last month, said in a tweet.

He later tagged Apple Chief Executive Officer Tim Cook's Twitter account in another tweet, asking "what's going on here?"

Musk also said "yes" in response to a user question on whether Apple was threatening Twitter's presence in the App Store or making moderation demands.

Apple did not immediately respond to requests for comment.

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

A rising list of firms from General Mills Inc to luxury automaker Audi of America have stopped or paused advertising on Twitter since the acquisition.

Musk, a self-described free speech absolutist, said earlier this month that Twitter had seen a "massive" drop in revenue and blamed activist groups for pressuring advertisers. Ad sales account for about 90% of Twitter's revenue.

The platform has in the past few days reinstated the account of former U.S. President Donald Trump, as well as comedian Kathy Griffin and U.S. House Representative Marjorie Taylor Greene.

The Trump reinstatement prompted a coalition of civil rights activists to say last week that they were urging Twitter's advertisers to issue statements about pulling their ads off the platform.

At a presentation for advertisers in May, some ad agencies and brands were already skeptical on concerns that Musk would scale back content moderation and security protection on the platform.

Illustration shows Elon Musk image on smartphone and printed Twitter logos
An image of Elon Musk is seen on a smartphone placed on printed Twitter logos in this picture illustration taken April 28, 2022. Reuters