By Idrees Ali
ROME, Feb 13 (Reuters) - Countries allied with the United States in the fight against Islamic State failed on Tuesday to come to a final agreement on what to do with foreign fighters captured in Syria who could pose a grave security threat if allowed to escape justice.
A meeting with around a dozen of defence ministers in Rome ended without agreeing how to deal with hundreds of foreign militants detained by the Syrian Democratic Forces (SDF) - a U.S.-backed alliance of militias - in Syria.
The U.S. delegation at the closed-door meeting, led by Defence Secretary Jim Mattis, had hoped to persuade allies to take more responsibility for the foreign fighters.
One option that has been discussed is to take detained militants back to their country of origin for prosecution - something western allies have shown little enthusiasm for.
"It was not resolved in a final way, it is being worked," Mattis told reporters travelling with him from Rome to Brussels.
Mattis said allies were engaged in dealing with the issue and a number of steps were under way, including repatriations. He added that there was no blanket solution to the detainee problem, and each case would have to be looked at carefully.
"The most important thing is we figure out how we are going to deal with this, that we can deal with it, we don't paralyse ourselves and just say there is nothing we can do ... That is the one thing I will say: doing nothing is not an option."
French officials have repeated that French fighters caught by SDF forces should be prosecuted by local forces and that Paris had no intention of bringing them back to their home soil.
"They are fighters. They are French, but they are our enemies. The conclusion is that they will be judged by those who they fought," Foreign Minister Jean-Yves Le Drian said on Feb. 7.
The names of the countries attending the meeting were not disclosed.
The foreign fighter issue received renewed attention when U.S. officials said the SDF had captured two of four militants known as the "Beatles" for their English accents.
"We don't want them going back on the streets, we don't want them on the street in Ankara, we don't want them on the street in Tunis, Paris or Brussels," Mattis said.
When asked whether the United States would consider moving some of the detainees to Guantanamo Bay, Mattis declined to comment. (Reporting by Idrees Ali; Additional reporting by John Irish in Paris; Editing by Robin Pomeroy)
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