Bosses behind upcoming comedy The Heat have come under fire in the UK for allegedly slimming down Melissa McCarthy's figure in its promotional poster.

The Identity Thief star's face and neck appear to be digitally altered in the new poster.

The image has caused a backlash from fans who are upset about the production company's decision to make McCarthy look more sexually appealing, even though the plus-size 42-year-old has never been ashamed of her curves.

Blogger Ali said the retouching job was "offensive" and "nasty".

"Nobody is unclear what Melissa McCarthy's body size is - she's plus-sized and proud," she wrote on British entertainment website The Shiznit.

"So why have the designers of this poster done their utmost to Photoshop (digitally edit) a good 30lbs (13.6kg) off of McCarthy's face?

"This is one of the worst Photoshop jobs I have ever seen, but it's not just offensively bad craftsmanship - the intention behind it is downright nasty."

This isn't the first time McCarthy's figure has reportedly been retouched - a one-sheet for her 2011 film Bridesmaids also depicted a thinner version of the Oscar nominee.

And it's not the first time McCarthy has hit the headlines over her weight.

In a controversial review of The Identity Thief, New York Observer film critic Rex Reed called McCarthy "cacophonous," "obese", "tractor-sized," and a "female hippo".

His comments caused outrage and a backlash on social media.

Sandra Bullock and Melissa McCarthy in the UK promotional poster for The Heat.

- WENN