Liam Payne's worries for Zayn Malik

Liam Payne is concerned his One Direction bandmate Zayn Malik is struggling to come to terms with fame, insisting the pop star has had a "terrible time" facing criticism online.

The boyband shot to fame in the U.K. on Simon Cowell's The X Factor in 2010, and have gone on to become a global sensation, catapulting all five members into the limelight.

Liam Payne insists most of the group love the attention they receive, but he worries about Zayn Malik, who recently temporarily deleted his Twitter.com account after reading a slew of nasty messages.

Liam Payne tells Britain's The Sun, "We've (the band) had such a good laugh together and achieved so much together. We're definitely like brothers.

"The only person I really worry about is Zayn, because I don't think he's quite accustomed to all of this. He had a terrible time on Twitter... I don't think he's quite adjusted to it yet. I'm sure he'll get it. He's my best mate. I've got to look out for him."