Mark Zuckerberg's Meta has launched its rival to Twitter, with the Threads app seeking to woo users from Elon Musk's troubled platform through an offer of lengthier posts, a handful of celebrity backers – and a strong resemblance to its competitor.

The Facebook and Instagram owner brought forward the app's debut by 15 hours to 7pm EDT in the US and midnight in the UK, making it freely available in 100 countries on the Apple and Google app stores, although regulatory concerns mean it will not be available in the EU.

Thread users will need an Instagram account to log in. Once they have signed up, they can choose to follow the same accounts they follow on Instagram, if they too have joined the new app. Meta said initial celebrity backers included Shakira and Gordon Ramsay, although a recent report suggested that Oprah Winfrey and the Dalai Lama had also been approached.

The app closely resembles Twitter visually, although some of the wording has been changed, with retweets called “reposts” and tweets called “threads”. Meta has not been averse to copying rival products in the past, including the 2020 launch of Instagram's Reels feature, noted for its similarity to TikTok's short-form videos.

Posts on Threads can be 500 characters long, compared with 280 for most Twitter users, videos of up to five minutes in length can be posted and a post can be shared as a link on other platforms. Users can unfollow, block, restrict or report others. Users can also filter out replies with certain words in them.