Nina Dobrev and Ruby Rose are embroiled in a "prank war".

Nina Dobrev's Instagram post

Nina Dobrev's Instagram post

The actresses are currently filming scenes for Vin Diesel's action movie 'xXx: The Return of Xander Cage' and it all kicked off on April 1 when tradition dictates that people should target their pals and play mischievous tricks on them.

The latest joke took place today (05.04.16) and saw Nina being outed as having a worrying infatuation with her 30-year-old co-star.

Ruby posted a video to her Instagram account which shows her entering Nina's make-up trailer and gasping in horror, as she stumbles upon dozens of portrait pictures of herself pinned to the walls and covering the bed of the 'The Vampire Diaries' star's private quarters.

Alongside the short clip, the Australian beauty wrote: "When you go to say hi to @ninadobrev but she has 100 photos in her trailer of you and it's awkward because you're trying to be professional.. #seekhelpnina #evillaughofastalker #wherestheshinetoo #ineedextrasecurity (sic)"

And in the video, Ruby says: "Are you ready to chill? Whoah, what the hell is this man! Dude this is not OK! Are you obsessed with me?"

Nina, 27, then reposted the video on her account and declared "war" on Ruby.

She said: "After I scared the crap out of her last week, she retaliated back. In true Narcissist fashion. By covering my entire trailer with photos of herself. Stay tuned y'all. The war has begun ... #ScareWars Watch your back Rose... Watch your back. @rubyrose #XXXtheMovie #PrankWars ... Ruby Strikes back (sic)"

Nina had previously scared the life out of her pal when she unexpectedly screamed in her face and captured her shocked reaction on camera.

Nina had shared the clip on Instagram on Friday (01.04.16) and wrote: "Going to have to wash your mouth out with Soap Missy. **Viewer Discretion is Advised** @rubyrose #ThoughtiWouldnt #ButiDid #ThatsOnYou #GotHer A Special pre April fools... Stay tuned for more, from the set of #XXXtheMovie ... Game on. Dobrev out (sic)".

Nina and Ruby play thrill seeking cohorts Rebecca Clearidge and Adele Wolff respectively in 'xXx: The Return of Xander Cage' which also stars Samuel L. Jackson NSA Agent Augustus Eugene Gibbons.