The cast of Friends is to reunite for a one-off special, more than 15 years since the show ended.

The unscripted episode will air on the HBO Max streaming service, launching in May. A date is yet to be announced.

Jennifer Aniston, Courteney Cox, Lisa Kudrow, Matt LeBlanc, Matthew Perry and David Schwimmer will all appear.

Perry posted on Instagram: "It's happening" with a photo of the cast from the 1990s. The rest of the cast then started sharing the same post.

Friends aired from 1994 until 2004. The final show was watched by 52.5 million viewers in the US, making it the most-watched TV episode of the 2000s.

The show has since picked up legions of younger fans through Netflix.

It was the UK's favourite streaming show and Netflix's second most popular show in the US in 2018.

Rumours of a reunion intensified after Aniston posted a photo of the cast together on Instagram in October.

HBO Max has now secured rights to the show's back catalogue for $425m (£339m).

"Guess you could call this the one where they all got back together - we are reuniting with David, Jennifer, Courteney, Matt, Lisa and Matthew for an HBO Max special that will be programmed alongside the entire Friends Library," said Kevin Reilly, chief content officer for the channel.

He said the reunion special will capture the spirit of a time when "friends - and audiences - gathered together in real-time".

The cast will be involved in producing the episode.

According to Variety, each actor is expected to receive $2.5m (£1.9m) for taking part in the special, which will be available when HBO Max - a new subscription streaming service - launches.

Fans of the show reacted with glee to the announced on social media.