Amazon, eBay and Alibaba are all among the world's biggest online retailers, but are developing at very different speeds, a new study has found.

ComScore, the research group, reported Amazon's portfolio of sites secured 282 million visitors across the globe in June 2011, equivalent to 20.4 percent of the whole internet population. More specifically, 35.4 percent of people logging on were from North America, 31.8 percent from Europe and 24.1 percent from Asia-Pacific, with Latin America on just over 4 percent, the same as the Middle East and Africa.

Ebay, the auction platform, had an audience of 224 million, or a 16.2 percent reach, with Europe providing 46.9 percent of this user base, North America on 34.6 percent and Asia-Pacific recording 11.7 percent.

Claiming third place was the stable belonging to Alibaba, a Chinese firm operating services including an eponymous business-to-business site and Taobao Mall, a business-to-consumer offering.