US politicians slammed Apple’s app store policies and threatened to unwind Facebook’s acquisition of Instagram during a high-profile congressional hearing which, while meant to be focused on digital competition, was dominated by political posturing.

The CEOs of Alphabet, Amazon, Apple and Facebook all testified at the hearing. It forms part of a congressional investigation of digital markets launched in June 2019, aimed at documenting competition issues; identifying anti-competitive conduct by dominant market players; and assessing whether revisions to current laws are necessary.

Apple chief Tim Cook insisted the company’s rules are transparent and “we treat every developer the same” when quizzed about bias in enforcing App Store policies and charging exorbitant commission.

He noted 84 per cent of apps do not pay commission, and fierce competition for developers prevented it from increasing the cut it takes from the remaining 16 per cent.

Facebook CEO Mark Zuckerberg, meanwhile, was grilled over the company’s acquisition of Instagram, with one politician arguing it was illegal because the company aimed to neutralise a competing service, and suggesting a break up may now be warranted.

Though it is unclear whether congressional action will follow, statements made in the hearing could have a bearing on ongoing competition investigations against the companies being conducted by the US Department of Justice and European Commission.