Coloured burgers have taken the fast food industry by storm, with hamburgers sandwiched between black, red and even pink buns.

However, the latest sandwich to appear on McDonald's menu in China comes in a slightly more subdued hue.

The Modern China Burger, which is only available until November 3, promises a mouthful of two pork patties, bacon and salad topped with tongue-tingling Sichuan pepper ketchup - all sandwiched between buns in a curiously industrial shade of speckled grey.

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McDonald's China have released the Modern China Burger on sale until November 3

One user posted the picture of his lunch with the title, 'burger or rock' #yum

The creation, made with the fluffy mantou-steamed bun the unappetising grey colour already has customers baffled.

Several have taken to social media to share pictures of the snack, under titles like 'burger or rock' as they struggle to understand why this particular shade, which is more reminiscent of a kitchen counter than a meal, was chosen.

The official advertising features a plump grey bun with layers of plump patties, crisp lettuce and oozing sauce.

But after trying the real thing, many customers remained unconvinced about the fast food company's attempt to stray away from the sesame seed bun they know and love.

Friends of one user asked 'what is it' next to his snap of the grey-topped Modern China Burger

Another diner's picture reveals a rather flat looking burger, that bears little resemblance to the ad

Grace Brown tweeted asking if the burger was inspired by concrete or pollution

Zen asked, 'why have a normal burger when there are burgers with buns the color of despair?

Grace Brown took to Twitter to question why the bun might be grey. She wrote: 'Hard to guess what inspired McDonald's Modern China Burger. Concrete? Pollution?'

Goatballoon added: 'Behold, "The Modern China Burger" what the hell kind of statement are they making with THAT??'

Zen tweeted: 'Why have a normal burger when there are burgers with byns that are the colour of despair.'

Trinaa Prasad joined the conversation saying: 'Who thought grey burgers were a good idea? Go home #McDonald's, you're drunk'

Angie compared the dull coloured patty to Homer Simpson's out of date and greying sandwich.