European bond funds also saw large outflows, while even the once-popular area of emerging market bond funds saw inflows fall, but remain positive, at €357 million, the fund tracker said.

May's markets were characterised by a number of worries, many of which were linked to Greek public debt problem and fears - not yet entirely suppressed - that the euro zone currency venture could break apart.

Mixed asset balanced funds benefited from the perception of them as a diverse source of return, showing robust inflows.

But despite the relative strength of the bond and mixed asset categories, the best overall sector of the month was German Equity with net sales of €6.5 billion.

"Although the DAX fell by 2.8 per cent in May, the top five funds in this sector were ETFs , suggesting savvy investors were buying when down … but also some short-selling distortions,” Lipper FMI said.

By far the strongest seller was iShares DAX with inflows of €4 billion, beating its homegrown competitor ETFLab DAX by €2.2 billion.