The European Union's top criminal prosecutor says member countries must update and harmonize their anti-terrorism laws to deal with European-born participants in Islamic jihad, as well as extremists acting alone.

Michele Coninsx, president of Eurojust, the EU's agency for judicial cooperation, told The Associated Press that despite much progress, the bloc is entering an era "where we see popping up new prosecution gaps" that she said could hinder cross-border efforts to fight terrorism.

Coninsx, a career prosecutor and counterterrorism expert from Belgium, said among the EU's 28 member nations, laws differ on how to deal with lone participants in terrorist actions.

She said EU countries' laws similarly vary on how to treat people leaving to fight with extremist groups in Syria or Iraq, or who have returned home from there.