Niall Horan's One Direction bandmates have all congratulated him on his debut solo single

Liam, 23, was the first to message Niall publicly, writing: "@NiallOfficial good luck boss give him all your support huge day for him proud of you boss," and Louis, 24, soon followed by tweeting: "Feeling super proud @NiallOfficial . You sound great ! Great to see you at your bday bash!!"

It wasn't long before Harry, 22, also messaged Niall, writing: "@NiallOfficial Ahhh, a lovely tune my friend. Congratulations. H."

Meanwhile, during an interview with Ryan Seacrest on KIIS FM, Niall admitted that One Direction are all concentrating on their solo projects but he insisted they haven't ruled out a reconciliation in the future.

He said: "I think for the foreseeable, we're all kind of doing our own thing. Everyone's enjoying doing their own thing. Harry did the movie [Christopher Nolan's 'Dunkirk'] and I'm doing this and Louis' got his things going on and so does Liam.

"But I still talk to them all the time, we still talk to each other. I saw Louis the other day. So for the foreseeable we're just doing our own thing but I definitely wouldn't rule it [a reunion] out."

Niall's comments came after Harry called One Direction "the most important, greatest thing that ever happened to me" but admitted he was unsure what the future holds for the band.

He told Another Man magazine: "I don't know.

"When we started people always asked, 'Where do you think you'll be in five years?' It's a difficult question to answer.

"I would never say we'll never do anything ever again but it's good for us to be exploring different things.

"Maybe at some point everyone will want to do something again but it'll be better if it happens naturally like, 'Hey, we all really want to do this again'. If that were to happen it would be amazing.

"I would never rule that out. It's the most important, greatest thing that ever happened to me, being in that band. It completely changed my life."