"There has been some increase, but not the numbers that we were expecting… The numbers are not as high as we expected," Wainwright said on the sidelines of the World Economic Forum (WEF) Annual Meeting in Davos.
The EU police chief added that his organization was not aware of the reasons behind the limited rise but was still on the lookout for any terrorists seeking to cross EU borders and commit attacks.
"We don't know how many of them died in combat, how many of them have already moved from that region to other regions, but not yet Europe. But there are large numbers of unaccounted foreign fighters. They is still potential to return and take part in terrorist activities. It remains a top concern for Europol," he said, stressing that it was uncertain how many militants were planning to come to Europe in the future.
Europe has been a significant source of foreign fighters who traveled to join Daesh ranks. The Soufan Group think tank estimates that some 6,000 people left Europe — mainly France, Germany and the United Kingdom — to wage war on the side of terrorists in Syria and Iraq. Hundreds of fighters have since returned home. Syrian authorities have also warned that terrorists are likely to pose as refugees to get into Europe.