Burger King has unveiled its first ever Lamb burger and is currently the only major fast food chain to try it out as a beef alternative.

But be warned, the new Lamb Flatbread Burger contains a whopping 708 calories, compared to a standard cheeseburger that has just 325 calories.

The ads for the Burger King Lamb Flatbread Burger prominently feature the words '1st Time Ever'.

It is thought to be the only lamb burger product on offer in major fast food chains in the UK but is only available for a limited time in UK Burger Kings.

The lamb burger is served on a rosemary flatbread instead of a bun and topped with 'spices, crisp salad, chilli ketchup and mint yoghurt sauce'.