Facebook behemoth Meta officially launched Threads, its text-based rival to Twitter, with more than five million sign-ups in the first few hours - but its release in Europe has been delayed over data privacy concerns.
Threads is the biggest challenger yet to Elon Musk-owned Twitter, which has seen a series of potential competitors emerge but not yet replace one of social media's most iconic companies, despite its epic struggles.
The app went live on Apple and Android app stores in 100 countries at 2300 GMT.
Accounts were already active for celebrities su ch as Jennifer Lopez, Shakira and Hugh Jackman, as well as media outlets including The Washington Post, Reuters and The Economist.
"Let's do this. Welcome to Threads," wrote Meta chief executive and Facebook founder Mark Zuckerberg in his first post on the new platform, which will run with no ads for now.
And he offered a shot across the bow at Musk -- the pair are known to be bitter rivals, and have even offered to meet each other in a fighting cage to wrestle it out.
"It'll take some time, but I think there should be a public conversations app with 1 billion+ people on it. Twitter has had the opportunity to do this but hasn't nailed it. Hopefully we will," Zuckerberg said.
Shortly thereafter, he wrote: "Just passed 5 million sign ups in the first four hours...".
