Zoe Kravitz developed a fear of heights on the set of 'Insurgent'.

The 'Divergent' actress has revealed that while she coped with jumping around apocalyptic rooftops in the first film in the franchise, she found filming stunts for the sequel much harder.

Speaking to the New York Post newspaper's PageSix about walking on a treacherous ledge, she explained: ''My body would not allow me to take that last step.

''We're harnessed in... but I couldn't do it. Stunt double!''

Meanwhile, Zoe's co-star Ansel Elgort has confessed that despite having starred alongside Shailene Woodley - who plays main character Tris in the film series - in three movies, there's never been any romantic tension between them.

He said previously: ''Me and Shailene have a really platonic relationship. I've never once wanted her sexually, which is nice.

''But for me, if a person is someone I'm attracted to, and she's my best friend, hopefully we're dating.''

'Insurgent' also sees the return of 'Divergent' stars Theo James and Kate Winslet and follows the story of Veronica Roth's novel of the same name.