A federal judge has ordered Google to tear down the digital walls shielding its Android app store from competition.

Alphabet, Google’s parent company, faces numerous legal challenges in the US that, together, threaten its core business.

Judge James Donato, who presided over the Epic vs. Google lawsuit that declared Google to be operating an illegal monopoly with its Google Play Store on Android last year, issued a final ruling on Monday requiring the company's mobile operating system to open up to third-party app stores for three years.