The pan-European FTSEurofirst 300 Index closed provisionally down 0.2 percent at 1,359.51 points, after Italy's FTSE MIB showed strong selling.
The FTSE MIB closed down unofficially 1.6 percent. European parliamentary elections are set to be contested at the end of the week, and Italy's prime minister, Matteo Renzi, is thought to be vulnerable, after weak economic growth data.
France's CAC and Germany's DAX closed provisionally up 0.3 percent and 0.4 percent respectively, after wavering throughout the day.
The health care sector saw the biggest losses. AstraZeneca shares closed down around 11 percent after the company rejected an improved offer from U.S. drugmaker Pfizer.
AstraZeneca pulled down the U.K's FTSE100, which closed provisionally down 0.1 percent.
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Mining shares also suffered after disappointing house price data out of China fueled concerns the world's second biggest economy was slowing.