British online fashion retailer ASOS posted a 37% rise in second quarter sales, buoyed by a better than expected home performance and strong overseas growth.

ASOS, whose celebrity fans include United States First Lady Michelle Obama, said retail sales had risen to £186 million in the three months to 28 February.

That was better than a market forecast for a 34% sales rise, and ahead of a 30% jump in its first quarter.

Sales had jumped by 41% in December alone after strong Christmas demand in Britain.

"Our UK performance remained ahead of expectations," Chief Executive Nick Robertson said.

"We remain positive in our outlook for the year to 31 August 2013 and continue to trade in line with expectations."

While the traditional high street has suffered as consumers worry about jobs and squeezed household incomes, online retailers are faring far better, with ASOS in particular bucking the gloom.

The firm, which targets young women looking to emulate the designer looks of celebrities like Nicole Scherzinger and Cara Delevingne, modestly described its performance in the first half of the year as "robust" and reaffirmed its positive outlook.

"We believe that ASOS is continuing to demonstrate its potential to become the online fashion destination for 20-somethings globally," Numis analysts said.

The group said its home market remained ahead of expectations in the second quarter with sales up 28% to £75.5 million, compared to 12% growth a year ago.

International sales rose 45%, up from a 34% rise in its first quarter, to almost £111 million.

ASOS said its retail gross margin slipped 50 basis points in the quarter but was expected to improve in the second half as last year's own-brand pricing reductions annualised.

Shares in ASOS, which have risen 77% in the last 12 months, closed yesterday at 3111 pence, valuing the business at around £2.5 billion.