The product immediately got taken up by several celebrities, following a push by Facebook to attract creative talent before launch: actress Jessica Alba posted a video with her family promoting her Honest Company's masks, while comedian Mindy Kaling showed off an intentionally underwhelming quarantine "workout" routine.

Reels' debut comes days after Microsoft said it was in talks to acquire TikTok's US operations from China's ByteDance. ByteDance has agreed to divest parts of TikTok, sources have said, under pressure from the White House, which has threatened to ban it and other Chinese-owned apps over data security concerns.

The launch escalates a bruising fight between Facebook and TikTok, with each casting the other as a threat.

Reels was first tested in Brazil in 2018 and then later in France, Germany and India, which was TikTok's biggest market until the Indian government banned it last month following a border clash with China. Facebook also tried out a standalone app called Lasso which did not gain much traction.

Similar to TikTok, Reels users can record short mobile-friendly vertical videos, then add special effects and soundtracks pulled from a music library.

Those similarities led TikTok Chief Executive Kevin Mayer to call Reels a "copycat product" that could coast on Instagram's enormous existing user base after "their other copycat Lasso failed quickly."

Facebook faced similar charges at a congressional hearing on US tech companies' alleged abuse of market power last week, with lawmakers suggesting the company has copied rivals like Snapchat for anti-competitive reasons.

Vishal Shah, Instagram's vice president of product, acknowledged the similarities in a Tuesday video conference call with reporters and said that "inspiration for products comes from everywhere," including Facebook's teams and "the ecosystem more broadly."

Australian Associated Press