Zayn Malik's bandmates have taken to Twitter to wish their friend a very happy birthday.

The One Direction heartthrob is celebrating turning 20 today - with Louis Tomlinson, Harry Styles and Niall Horan all sending their congratulations to the birthday boy.

Tomlinson was the first of the group to tweet his greetings to Malik, writing: "Massive happy birthday to my brother @zaynmalik . See you in a bit ! Huge love ! (sic)."

Horan also took to the social networking site to gush: "Massive happy birthday to one of my best mates! @zaynmalik ! 20 now ! Wohoo! Pints (sic)."

Styles wrote: "HAPPY BIRTHDAY BAD BOIIII!! Happy 20th to a great great friend. Had some amazing times, looking forward to more! Love you bro .x (sic)."

Liam Payne is the only band member yet to send birthday wishes to Malik on Twitter.

Aside from their greetings to Malik, Tomlison also added a message to Irish charmer Horan, revealing: "Just want to say a belated congrats to @niallofficial for passing his driving test ! Smashed it ! (sic)."

Watch the video for One Direction's 'Kiss You' here: