Zalando, Europe's largest dedicated online fashion retailer, lifted its full-year revenue forecast after sales growth accelerated further in the first half.

The Berlin-based company now expects revenue to grow 28-31% in 2015, having previously guided for a 20-25% increase.

"Zalando is powering ahead to take full advantage of the great opportunities in European fashion e-commerce," board member Rubin Ritter said in a statement on Thursday.

The world's No. 6 in apparel and footwear internet retailing affirmed its full-year target for an adjusted operating margin of 4.5% after posting a 4.1% margin for the second quarter.

Profitability in the second quarter suffered because the group temporarily offered more generous payment terms to customers which resulted in a higher rate of defaults.

Adjusted earnings before interest and tax (EBIT) decreased to 30.2 million euros (£21.6 million) in the April-June period, down from 35.1 million (£25 million) euros last year. Second-quarter revenues grew 34.1% to 733 million euros (£523.7 million).