It’s a rocky economy on the Continent these days with some economists forecasting a recession for the European Union in 2012. But the current economic conditions don’t appear to be scaring away U.S. web merchants looking to build a base or expand their operations in European online retailing.

By many measures not only are more big American e-commerce brands setting up shop in Europe for the long haul, they also are looking to leverage their names and deeper pockets to take market share away from European online retailers, according to research contained in Internet Retailer’s newly published 2012 Top 400 Europe.

Led by Amazon (No. 1) the 33 U.S. companies ranked among Top 400 Europe retailers grew their collective sales about 27% in 2011 to 20.2 billion euros ($26.1 billion) from 15.9 billion euros ($20.6 billion) in 2010. And U.S. web merchants grew faster than their European rivals, accounting for 25% of sales among Top 400 Europe merchants last year, compared with 23.4% in 2010.

By far, Amazon remains the biggest U.S. web merchant competing in Europe, with Internet Retailer-estimated sales that grew year over year 37.2% to 12.9 billion euros ($16.7 billion) in 2011 from 9.4 billion euros ($12.1 billion). But other U.S. online retailers, especially several niche merchants, also made big strides in penetrating the business-to-consumer e-commerce market in 2011. For the 2011 fiscal year ended June 30, Vistaprint Ltd. (No. 59) grew its European web sales 24.5% to 248.6 million euros ($321.7 million) from 199.7 million euros ($258.5 million) in 2010. Vistaprint, a specialty web merchant of custom printing and related small business services, now has separate e-commerce sites for 17 countries, a printing center in the Netherlands and a headquarters with more than 300 employees in Spain.

Despite a common currency used by 17 European countries and the fact that 27 countries participate in the European Union, an economic and political confederation, European business-to-consumer e-commerce remains a fragmented market. “U.S. retailers will have to develop web strategies for most individual European countries for the foreseeable future and develop a local value proposition that tells shoppers they understand who they are,” says Christine Bardwell, research manager, retail insights, for research and consulting firm IDC. “The mature e-commerce markets of the U.K., France and Germany are as different in nature from the growing, but far less developed e-commerce markets in Southern Europe.”

For the first time the Top 400 Europe is available in three forms: print, digital and as part of the all-new and completely updated Top500Guide.com. Information on how to order the top 400 Europe is available here.