European shares finished the session 1.5 percent lower.The decline was led by banks due to renewed concerns over their exposure to Dubai World. Major Greek banks slumped between eight and 10 percent following a downgrade of Greece’s credit ratings by Fitch. Other factors included weak German industrial output, a slowdown in the recent increase in UK retail sales and cautious comments from Federal Reserve Chairman Ben Bernanke a day earlier. He had said the US economy faces “formidable headwinds,” including a weak jobs market and tight credit conditions. Commodities producers fell as crude oil and metal prices retreated because the dollar rose against other currencies. BG Group, BP and Total all lost value along with mining companies Anglo American, BHP Billiton and Xstrata.