The instant messaging app Telegram registered 70 million new users during Monday’s Facebook blackout, its Russian founder said, as people around the world flocked to the encrypted service. “The daily growth rate of Telegram exceeded the norm by an order of magnitude, and we welcomed over 70 million refugees from other platforms in one day,” Pavel Durov wrote on his Telegram channel. The app jumped 55 spots on Monday to top the US iPhone download chart, according to Sensor Tower, an app intelligence company. Telegram, which says it prioritises users’ privacy and security, was founded by the self-described libertarian Durov in 2013 and maintains a hands-off moderating philosophy. “I am proud of how our team handled the unprecedented growth because Telegram continued to work flawlessly for the vast majority of our users,” Durov said, although he admitted the service did experience some difficulties after the surge of new users. “Some users in the Americas may have experienced slower speed than usual as millions of users from these continents rushed to sign up for Telegram at the same time,” he added. Durov, who previously founded Russia’s biggest social network, VKontakte, together with his brother, Nikola, but left the country after being pushed out under government pressure, has repeatedly criticised Facebook’s WhatsApp messenger’s safety and urged users to remove the app from their smartphones. While Telegram, which is based in Dubai where Durov resides, did not publish its data on new users, experts confirmed they saw an unprecedented boom in users on Monday. “Based on our research, over 50 million new users joined the app following the Facebook blackout. This is by far the biggest surge Telegram has ever seen,” said Yuri Kizhikin, the founder of the Moscow-based TGStat analytical centre. “We also see that those that joined Telegram have been actively using it over the last two days,” Kizhikin added. Other alternatives to WhatsApp and Facebook also gained traction during the outage, with millions of new users joining the Signal messaging app. It is not the first time Telegram has experienced a rapid influx of new users. In January, the app said it added more than 25 million users following concerns over a new WhatsApp privacy policy and confusion about whether the policy would mandate data sharing with Facebook. Telegram then announced that it topped 1bn downloads and had 500 million monthly active users. Telegram also gained popularity among the far right in the US after tech companies including Twitter and Facebook started to shut down accounts and groups of concern. Due to its privacy credentials, Telegram has long been used by pro-democracy activists in countries including Belarus, Hong Kong and Iran. In Russia, the Kremlin was forced to lift a ban on the widely used app after unsuccessfully trying to curtail it for years. However, Kremlin critics have recently accused the app of bowing down to the authorities after it blocked a bot that told supporters of the jailed opposition figure Alexei Navalny which candidate they should back to unseat Kremlin-aligned politicians during September’s parliamentary election. Durov defended the move, saying the decision was based on Russia’s ban on campaigning during voting. Durov also said he was following Apple and Google, which had earlier deleted Navalny’s apps from their online stores. Telegram has recently sold more than $1bn in bonds to international investors, with Russia’s state-run Direct Investment Fund now among one of the firm’s minor backers.