Justin Bieber brushes off criticism over Calvin Klein photos

Justin Bieber is laughing off critics of his Calvin Klein images.

A series of photographs of the 20-year-old heartthrob were recently released by the fashion house showing the hunk posing in his underwear as he was named as the new face of the brand, and he has now laughed off speculation the images were digitally enhanced to improve his muscles and package.

Posting a muscled image on Instagram of himself wearing only a towel to cover his modesty, he wrote: "Photoshop lol."

The "As Long As You Love Me" hitmaker's physique has been doubted since the photographs were released, and last week gossip website breatheheavy.com published an image which they claimed was an original shot of the singer before it was edited, showing him with considerably smaller muscles and a less impressive bulge in his underwear.

However, the website quickly pulled the image after Justin's team threatened to sue them for damaging his brand.

Critics of the images include Hollywood actor Mark Wahlberg's wife, Rhea, who took to her Twitter account last week to say she thought her husband looked better in his Calvin Klein shoot, which took place in 1992.

She wrote: "My baby was the 1st and the best And not to mention......wow the retouching......(sic)."

Famous underwear model David Gandy, 34, has also come out in support of the actor's physique in his campaign, saying Justin can't compare because his muscles aren't as defined.

He told The Sun newspaper: "Mark is very strong. I can't imagine Justin having as many muscles."