Etail fashion giant Asos sales increased 34% in its fourth quarter with international sales driving much of the growth.

For the three months to March 31, UK sales jumped 4% while international sales soared 63%.

The quarter was up against particularly strong year-on-year comparisons with the fourth quarter of last year up 69%. Asos said gross margin was “significantly ahead” year-on-year.

For the full year sales rose 49%, with the etailer expecting pretax profit to be in line with expectations.

International sales once again drove much of the growth with sales increasing 103% over the year and UK sales rising by 7%. International sales made up 59% of total sales for the year.

By the end of the quarter international sales represented 62% of total sales, up from 51% last year.

Asos chief executive Nick Robertson said: “I am pleased to report a strong fourth quarter performance for both our UK and international businesses, particularly as we annualised against the introduction of global free shipping last year.

“Profit before tax and exceptional items for the full year to 31 March 2012 is expected to be in line with expectations. We remain committed to our global expansion plans and approach the new financial year with confidence.”

The etailer has changed its accounting reference date and financial year end from March 31 to August 31. It said the board had taken this decision to enable the company’s external reporting period to align with the buying seasons in the fashion industry.