A French navy vessel has detected the black boxes of a Yemenia Airways plane that crashed into the Indian Ocean near the Comoros Islands, the ship's captain said Thursday.

Comoran and French authorities, meanwhile, were still investigating the cause of the June 30 crash that left a 12-year-old girl as the only known survivor out of 153 people aboard.

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The "Beautemps-Beaupre" hydrographic and oceanographic frigate mapped the sea floor and handed its finding over to Comoran authorities and to the French aviation agency BEA, ship Capt. Marc Reina told The Associated Press.

"A cartography has been completed and the recorders have been pinpointed," Reina said by phone from the French island of Reunion in the Indian Ocean, where his ship has docked before returning to its base in Djibouti.

The plane's cockpit voice and flight data recorders, known as black boxes, could help explain why it crashed as it tried to land in heavy winds. But they lie in waters too deep for divers, requiring specialized robots to bring them up to the surface.

Reina said underwater robots sent by the French navy to Comoros should begin operating in August.

Yemenia Flight IY626 crashed on its way from San'a, Yemen, to Moroni, Comoros. Many of those aboard were from France's Comoran community and had embarked in Paris or Marseille before changing planes in Yemen.

French Comoran community leaders have complained that Yemenia Airways planes weren't safe. Yemenia officials have denied the claim and complained that French authorities helping with the search for debris and bodies have not been sharing their findings with Comoran and Yemeni authorities.

Investigators have found wreckage from the plane near two Kenyan islands, hundreds of miles away from the Cormoran archipelago. At least 27 bodies had been recovered, including some that had drifted to Tanzania, according to Yemen's aviation accidents committee.