Europe should set up a transnational data network to keep better track of Islamist militants who may have returned from Iraq and Syria, the head of German police said on Saturday.

Holger Muench, president of the BKA federal police, told Redaktionsnetzwerk (RND) Deutschland, that Europe's IT security architecture was insufficient.

Only around half of the European Union's 28 member states automatically compare finger prints or DNA profiles, he said.

"We need to become quicker and better here. EU states should work together via a joint transnational data network," he said.

Muench said he was also concerned that a network of jihadists was being formed of fighters who have returned to various European countries.

"These people got to know one another in Iraq or Syria and are maintaining their contacts and relationships here in Europe," he told RND.