Pop star Katy Perry is said to have reunited with her ex-boyfriend Rob Ackroyd during the UK leg of her Prismatic World Tour.

The 'Roar' hitmaker, who Ackroyd dated back in 2012 after the pair met at the Coachella music festival, is reportedly spending time with him, reported Contactmusic. Katy Perry, 29, was spotted kissing and cuddling him at an afterparty in the exclusive backstage area of London's O2 Arena to celebrate the end of the European leg of her tour.

"Katy and Rob seemed to be very much back together at her party on Saturday night. They were inseparable, kissing, flirting and cuddling away in front of the roadies, celebs and friends at the bash. There were a fair few famous faces in the room but Katy and Rob only had eyes for each other," a source said.

Ackroyd, 30, also shared a picture of one of Perry's gigs on twitter praising the singer with the caption, 'Killed It'.