European stocks tumbled Monday on renewed fears of a Greek exit from the eurozone and the euro struck a nine-year low against the dollar as the ECB appeared on course to further prop up the single currency. London's benchmark FTSE 100 index shed 2 percent compared with Friday's close to end the day at 6,417.16 points, while Frankfurt's DAX 30 dropped 2.99 percent to 9,473.16 points.