Online fashion giant Asos’ retail sales rocketed 41% to £78m across its Christmas trading period, as the UK division posted “particularly strong” trading in December.

UK retail sales soared 34% to £35.6m, while retail sales at its international business surged 47% to £42.4m.

Total revenue at the etailer was up 40% to £79.8m, as the number of orders despatched increased 40% to 2 million against the same period last year.

But Asos revealed retail gross margin was down 29 basis points year on year.

Asos chief executive Nick Robertson said: “I am pleased to report very strong trading during December with retail sales up 41% to £78m.

“Our UK performance was particularly strong, up 34%, which continues to be driven by better conversion of traffic alongside continued investment in both our proposition and pricing. Our International business grew by a healthy 47%.

“We remain positive in our outlook for 2012/13 as we continue our journey to becoming the number one online fashion destination for twenty-somethings globally.”