London, June 11 - Katherine Heigl, whose movie Killers recently premiered in London, says acting in the action-comedy flick was "painstaking".

"It's really fun but it's little bits at a time, so it's a little bit painstaking for me. I like those dialogue scenes where you're sort of bantering," The Mirror quoted Katherine, as saying.

The former Grey's Anatomy actress added: "One of my favourite scenes of the movie was the pregnancy test scene because that was just sort of Ashton and I improv-ing. I thought that we were really good at bickering together!

"The action side of it that requires everything being re-set and put in its place ... so it can take a day or two to do one tiny little thing."

Katherine is paired opposite Ashton Kutcher in Killers.

The film hits cinemas on June 18. (ANI)