ATHENS, Greece (AP) — Greece’s state ombudsman said Thursday that it’s launching an independent investigation into the coast guard’s handling of a maritime tragedy in June in which hundreds of migrants trying to reach Europe in an overloaded boat are feared to have drowned.

The independent authority said that it took the decision following “the expressed denial” of the Greek coast guard to initiate a disciplinary investigation in response to the ombudsman’s written requests.

A military court with jurisdiction over Greece’s navy and coast guard is conducting a preliminary investigation into the June 14 shipwreck, from which 104 survivors and 78 bodies were recovered.

Up to 750 people were believed to have been on the rusty fishing vessel, mostly below decks, when it sharply listed and quickly sank in the night. That would make it one of the worst disasters of its kind in the Mediterranean.

The court is also handling a lawsuit by 40 survivors, who accuse the coast guard of failing to prevent the shipwreck and loss of life.

Activists and human rights groups have strongly criticized the coast guard for its handling of the operation, even though a patrol boat escorted the trawler for hours and was present when it sank in deep waters 75 kilometers (45 miles) off southwestern Greece.

The coast guard said that the sinking appeared to follow a mass movement of people on deck to one side, which tipped the overcrowded trawler over. It also said the migrants, who were trying to get from Libya to Italy, had earlier refused assistance.

But some survivors said that the ship foundered during a botched attempt to tow it — which the coast guard strongly denied.

The ombudsman said there was a need for “absolute transparency” on how Greek authorities handled the operation.

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