WASHINGTON (AFP) - Dozens of US prosecutors are being sent to the Balkans, Middle East and North Africa to help track down militant fighters coming from Syria, the outgoing attorney-general said Thursday.

Washington has repeatedly voiced concern about hardened Islamists emerging from war-torn Syria and using their Western passports to attack the United States and its allies.

Prosecutors and senior law enforcement advisers were being despatched to "key regions," Eric Holder said after meeting European officials in Washington.

"These personnel will provide critical assistance to our allies in order to help prosecute those who return from the Syrian region bent on committing acts of terrorism."

The cooperation includes "information sharing, investigations and prosecutions, and countering violent extremism."

A senior Justice Department official said about 70 prosecutors were working in several countries including Albania, Bosnia, Croatia, Kosovo and Serbia, as well as in North Africa and the Middle East.

A regional prosecutor specializing in anti-terrorism will be based in Albania to coordinate work in the Balkans and the director of the International Institute for Justice and the Rule of Law has moved to Malta.

"They're not there to put a US legal system in place," the official said.

"Their goal is to ensure that the country has in place statutes that are consistent with the UN counterterrorism convention, with the global terrorism forum best practices."