Apple spends over $100 million per year on Twitter adverts, sources told Bloomberg.
Apple spent $48 million on Twitter ads in Q1, making it a key revenue stream, per the Washington Post.
Musk claimed on Monday that Apple has mostly paused advertising on the platform.
Apple spending on Twitter adverts exceeds $100 million per year, Bloomberg reported amid a growing feud between Twitter's owner Elon Musk and the tech giant.
Apple, the largest tech firm in the world, is a vital source of revenue for Twitter. It had an entire team of staff dedicated to its relationship with Twitter and spends over $100 million on ads annually, people familiar with the matter told Bloomberg.
In the first quarter of the year, Apple was Twitter's top advertiser and spent $48 million on ads, the Washington Post reported. Apple's spending on the platform contributed to over four percent of Twitter's revenue that quarter, the Post said.
Twitter has potentially lost this crucial revenue stream as Musk tweeted on Monday that Apple had "mostly stopped advertising on Twitter," adding: "Do they hate free speech in America?"
"What's going on here, Tim Cook?" - Musk asked in a follow up tweet.
It is unclear whether Apple has actually removed ad spending from Twitter, and neither Apple nor Twitter immediately responded to requests for comment from Insider.
Musk outlined in a tweet that Apple had additionally "threatened to withhold Twitter from its App Store, but won't tell us why."
The billionaire CEO took aim at the tech firm on Twitter on Monday criticizing it's 30% fee which charges companies like Twitter for purchases made in Apple's App Store. Musk also published a poll asking users whether Apple should "publish all censorship actions," with nearly two million users voting so far.
Musk had complained about App Store fees being "too high" earlier this month. Shortly afterwards, Phil Schiller, a high-profile Apple executive managing the App Store, deleted his Twitter account, which had over 200,000 followers.
If Twitter is booted off the App Store, it will lose access to 1.5 billion devices around the world, Bloomberg said.
Apple joins a number of companies that have suspended advertising on Twitter including Audi, Pfizer, General Motors, Volkswagen, and more.