It is the little piece of indulgence that is also said to boast its very own health benefits.

Sales of dark chocolate have almost doubled in two years as health-conscious consumers buy into the image and choose quality over quantity.

Latest figures show £85m of dark chocolate was sold in Britain last year, up 96% on 2005.

Luxury brands of milk and white chocolate are also flying off the shelves, with sales at the top end of the market rising 46% in the two years to £140m last year, according to research by Mintel.

It said companies such as Kshocolat, which was formed in Glasgow seven years ago, Hotel Du Chocolat and Plaisir Du Chocolat had helped "reinvigorate" the premium chocolate industry and turn Britain into a nation of "chocolate buffs".

"Although dark chocolate is still high in sugar, it is rich in antioxidants and is lower in fat than milk chocolate. Dark chocolate now has the reputation as being a healthier alternative to other chocolate and this has really struck a chord with Britain's chocoholics," said Mathilde Dudouit, senior market analyst at Mintel.

"Brits may not be eating chocolate as often as they used to but they are certainly splashing out more on premium varieties. The trick today is to eat less but to go all out when indulging so that it really is a luxurious treat."

Health concerns over rising levels of obesity led to a drop in value of the chocolate industry in 2003 and Mintel said that people are still cutting back on the amount of chocolate that they eat.

But analysts added that the growing trend towards more expensive, dark and luxury chocolate treats had helped boost total spending recently, with total sales of chocolate growing by 10% in the two years to 2007. The British market is expected to be worth £2.23bn by the end of this year and will grow by 17% in the five years to 2013.

Kshocolat has grown from its origins in Glasgow to sell its products, which include chocolate bars, drinking chocolate and gift boxes, in around 8000 outlets across 22 countries.

Simon Coyle, who founded the company, said: "When we launched Kshocolat all the chocolate in the gift sector seemed to be very fussy and overcomplicated. I thought there was a gap there. People do appreciate and understand the reason for spending a bit more on quality food.

"At first our brand was considered extremely premium, almost inaccessible to some people. Now we have a strong customer base from the high end such as Harvey Nichols to Sainsbury's. We have grown very significantly in the last 12 months.

"Eating habits have developed in the last few years and people are more aware of what they consume. They know that they can eat dark chocolate, substitute the sugar and milk content, and it is a lot better for you than milk chocolate."