Google on Friday suspended the Parler social networking service from its app store, citing posts inciting violence and demanding robust content moderation from the app favoured by many supporters of US President Donald Trump.
Apple on Friday also gave the service 24 hours to submit a detailed moderation plan, pointing to participants using the service to co-ordinate Wednesday's siege of the Capitol building in Washington.
The actions by the two Silicon Valley companies mean that the network seen as a haven for people expelled from Twitter could become unavailable for new downloads on the world's main mobile phone app stores within a day. It would still be available in mobile browsers.
Right-leaning social media users in the US have flocked to Parler, messaging app Telegram and hands-off social site Gab, citing the more aggressive policing of political comments on mainstream platforms such as Twitter and Facebook. Twitter permanently suspended Mr Trump's account on Friday.
In suspending the service, Google, whose software powers Android phones, cited its policy against apps that promote violence and gave recent examples from Parler, including a post on Friday that began "how do we take back our country? About 20 or so co-ordinated hits" and another promoting a "Million Militia March" on Washington.
Parler's chief executive John Matze said in a post on Friday that Apple was applying standards to Parler that it did not apply to itself.
Google said that "for us to distribute an app through Google Play, we do require that apps implement robust moderation for egregious content".
"In light of this ongoing and urgent public safety threat, we are suspending the app’s listings from the Play Store until it addresses these issues," it said.
In a letter from Apple's App Store review team to Parler, Apple cited participants of the mob storming the Capitol building.
"Content that threatens the well-being of others or is intended to incite violence or other lawless acts has never been acceptable on the App Store," Apple said.
Apple gave Parler 24 hours to "remove all objectionable content from your app ... as well as any content referring to harm to people or attacks on government facilities now or at any future date".
The company also demanded that Parler submit a written plan "to moderate and filter this content" from the app.
Apple declined to comment.
Mr Matze, who describes himself as libertarian, founded Parler in 2018 as a "free-speech driven" alternative to mainstream platforms but began courting right-leaning users as prominent supporters of Mr Trump moved there.
Those who joined include commentator Candace Owens, Mr Trump's lawyer Rudy Giuliani and right-wing activist Laura Loomer, who handcuffed herself to the door of Twitter's New York office in November 2018 to protest against decision to bar her from the site.
In November, conservative activist Rebekah Mercer confirmed that the she and her family, which includes her father and hedge fund investor Robert Mercer, provided funding to Parler.
"Apparently they believe Parler is responsible for all user-generated content on Parler," Mr Matze said.
"Therefore by the same logic, Apple must be responsible for all actions taken by their phones. Every car bomb, every illegal phone conversation, every illegal crime committed on an iPhone, Apple must also be responsible for.
"Standards not applied to Twitter, Facebook or even Apple themselves, apply to Parler."
