The monkey trainer on 'Friends', who worked on "about five episodes", is coming for the actor who previously stated his hatred of working with his simian co-star.

Katie and Monkey are the names of the two female capuchins who played opposite David Schwimmer as Marcel the Monkey on 'Friends'. The actor has made it clear in the past that he disliked working with the animals, simply telling Entertainment Weekly in 1995 "I hate the monkey".

Schwimmer's annoyance of working with the monkeys was once again touched upon during the recent 'Friends' reunion episode. The actor, who played Ross Geller in the sitcom, voiced how scenes would have to be reset a number of times because the monkey didn't hit its mark.

He said: "Here is my problem: The monkey, obviously, was trained. It had to hit its mark and do its thing right at the perfect time. What inevitably began to happen was we would all have choreographed bits kind of timed out, and it would get messed up because the monkey didn't do its job right. So we would have to reset, we'd have to go again, because the monkey didn't get it right."

Now, however, the animal trainer who worked on the series, Mike Morris, says that David Schwimmer could have been "jealous" of how much attention Marcel the Monkey was getting on set. He told The Sun: "This is just my opinion... [but] the first couple episodes [Schwimmer] was pretty friendly with the monkey, and after that, the monkey was getting a lot of laughs, and either it was throwing him off or [he was] getting a little jealous. I don't know. One of those two things."

"It is true that we prefer that actors don't become too friendly with the monkey. An actor is a prop to the monkey and has to work with that prop. We don't want them to become friends because then [monkeys] think, 'Oh, it's my friend, I don't have to work… They just want to go hang out with their friend instead of doing what they're supposed to do. It's not out of spite or malice."

Morris further went in on Schwimmer, adding that Jennifer Aniston and Matt LeBlanc, who also shared scenes with the monkeys, were "a pleasure to work with".

Unfortunately, the capuchin called Monkey recently died of cancer. Katie, however, is still working. The animal trainer continued: "So Schwimmer was talking ill of the dead when he made those comments [on the reunion]. I find it despicable for him to still be speaking ill of her. Him still talking ill about the monkey all these years later seems pretty childish to me… It was one season over 25 years ago, it's time to let it go."

Further adding fuel to his dislike of Schwimmer, Morris added he never watched 'Friends' or the reunion because of the actor.

All seasons of the sitcom can be watched via Netflix; the 'Friends' reunion is available on Sky and NOW.