BERLIN, Germany — German e-commerce investor Rocket Internet saw first-half sales continue to grow strongly at several of its leading start-ups although they kept bleeding cash.

Europe's largest Internet company, founded in 2007, is viewed as a potential launch pad for future stock market listings from online fashion to food delivery although several mooted initial public offerings have been put on ice recently.

Sweden's Kinnevik, one of the biggest investors in Rocket Internet, said first-half revenues for the Global Fashion Group, which incorporates five online fashion firms in emerging markets, rose 63 percent to 418.2 million euros ($469.5 million), while the operating margin improved slightly to a negative 36.1 percent from 37.4 percent a year ago.

Furniture websites Home24 and Westwing saw revenue rise 98 percent to 117.6 million euros and 48 percent to 108.8 million euros respectively, while their operating margins deteriorated, to negative 31.7 percent for both firms.

By Emma Thomasson; editor: Maria Sheahan.