The International Criminal Court on Monday ordered the tribunal's prosecutor for a second time to reconsider whether Israel should face charges over a deadly 2010 raid on a flotilla carrying aid
to Gaza.
Prosecutor Fatou Bensouda said in 2014 that she would not prosecute Israel over the incident, saying it was "not of sufficient gravity" - which means the case could be determined as inadmissible before the ICC.
Bensouda again affirmed the decision in 2017 after judges said she must take another look at the case.
But in a fresh setback for Bensouda after a number of high-profile failures, appeals judges ruled on Monday that she must once more examine whether to bring Israel before the Hague-based court.
"The prosecutor is directed to reconsider her decision by December 2, 2019," presiding appeals judge Solomy Balungi Bossa told the court, adding that a majority of judges had backed the move with two dissensions.
Nine Turkish pro-Hamas militants died when Israeli marines stormed the Mavi Marmara, among eight ships trying to break a naval blockade of the Gaza Strip. One more died in hospital in 2014.
The case was first filed by the Comoros, where the ship was registered.
Ties between Israel and Turkey crumbled after the raid but they later agreed to end the row after secret talks.
Israel offered an apology over the raid, permission for Turkish aid to reach Gaza through Israeli ports, and a payout of $20 million (18 million euros) to families of those killed.