LONDON (Dow Jones)--Online fashion retailer Asos PLC (ASC.LN) Wednesday posted a 48% jump in first-quarter group revenue, helped by a more than doubling of overseas sales, although it cautioned that it is too soon to know if this level of momentum will continue for the rest of the fiscal year. Asos, whose core customers are fashion-savvy 16 to 34 year-old women looking to recreate catwalk styles for a fraction of the price, said group revenue rose to GBP65.8 million in the three months to June 30 from GBP44.6 million a year earlier Group revenue includes retail sales, postage and packing income and third party revenue. Retail sales climbed 54% to GBP61.7 million from GBP40 million a year earlier. The bulk of the growth was driven by a more than doubling of sales from overseas, which jumped to GBP22.9 million from GBP10.9 million a year earlier. Asos said international sales now form 37% of its total retail sales. U.K. sales remained solid, rising 32% to GBP38.8 million from GBP29 million. Despite the strong start to fiscal 2011 trading, Asos Chief Executive Officer Nick Robertson said in a statement that it is too early in the fiscal year to assume these levels of sales will continue. Nonetheless, he said the company remains confident of "another year of excellent progress." -By Hannah Benjamin, Dow Jones Newswires; 44-20-7842-9298; [email protected] (END) Dow Jones Newswires July 14, 2010 02:18 ET (06:18 GMT)