Shoppers couldn't believe their eyes when they saw Marks & Spencer was selling half-a-tonne of Brussels sprouts for a fraction of the price.

The promoted weight of sprouts was listed as 500kg for just 40 pence.

But that weight of veg - the equivalent of 50,000 sprouts - would be enough to feed the entire British armed forces at Christmas.

In a newspaper advert for a Christmas dinner, the supermarket listed their 40p Fresh Market Specials.

The offer included 1.5 kilos of Chopin potatoes, a kilo of carrots, 500 grams of parsnips and a single broccoli head.

On top of this, the fresh veg deal also featured a whopping "500kg" bag of sprouts.

But the deal wasn't a Christmas miracle and bosses have blamed it on an unfortunate misprint.

An M&S spokesperson said: "We aim to deliver value, but clearly this is a misprint and we’re sorry for any confusion caused."

The chain instead confirmed that a 500g bag of Brussels sprouts is available for 40p.

The Advertising Standards Authority (ASA), who regulate adverts in the UK, said M&S would not actually be expected to provide that amount of sprouts.

An ASA spokesman said: "It seems like a situation where it is a simple mistake and consumers would likely recognise this too.

"No doubt the advertiser would immediately rectify it and it is unlikely we would expect the advertiser to provide that amount of sprouts."

According to Defence Equipment and Support, British armed forces cook up half-a-tonne of sprouts each Christmas, along with 4.8 million sausages, 3,000 turkeys and 1.3 million potatoes.