The singer has been signed off with stress, meaning he’ll miss three concerts due to take place in the Far East during the next week.
A spokesman for the band tells The Sun: "Zayn has signed off with stress and is flying back to the UK to recuperate. The band wish him well and will continue with their performances in Manila and Jakarta."
The news comes just hours after Zayn was forced to take to Twitter, to reject speculation over whether he’d cheated on his fiancée Perrie Edwards.
A source adds: “Zayn finds it tougher than the rest of his band-mates dealing with fame.
“Having his every movement scrutinised causes great anxiety and the pictures which surfaced with the fan yesterday was the final straw.
“He did nothing wrong but the amount of criticism he received was simply too much. He needs to get away.
“The band’s management accept he needs some time off so he’s been sent home with their blessing.”
Zayn is expected to rejoin his bandmates before their Cape Town concert, on 28 March.
On Wednesday evening, pictures appearing to show Zayn holding a mystery girl’s hand during a night out in Thailand emerged online.
Fans later identified the blonde woman, when she posted a snap of herself and Zayn on Instagram.
The Bradford-born singer took to Twitter, writing: “I'm 22 years old... I love a girl named Perrie Edwards. And there's a lot of jealous fucks in this world I'm sorry for what it looks like x.”
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