The track, title 'Drag Me Down', was dropped on iTunes and Spotify worldwide at 6.30am (GMT) this morning (31.07.15) and is the first song they have released as a four-piece, following the departure of Zayn Malik in March.

Announcing the news on Twitter, band member Liam Payne wrote: ''Bit of a surprise ! Check out our new single! It's called Drag Me Down & I hope you love it as much as we do (sic).''

Niall Horan also tweeted: ''Finally we get to say this ! have waited a long time but our new single Drag Me Down is out !!! (sic)''

The song will feature on the band's forthcoming fifth studio album which is expected to be released in November.

The group - also featuring Harry Styles and Louis Tomlinson - are currently on the US leg of their 'On The Road Again' stadium tour.

The release of the surprise single - which is available to buy now - comes just a day after former band member Zayn Malik signed a solo record deal and suggested he was never allowed to be himself during his four years in the band.

He tweeted: ''I guess I never explained why I left , it was for this moment to be given the opportunity to show you who i really am! #realmusic #RCA !! ... #REALME (sic)''