A prosecutor in Turkey has prepared indictments and recommended life sentences for four senior Israeli officers over the killing of nine activists aboard a Gaza-bound aid flotilla forcibly intercepted by Israeli commandos two years ago, Turkish news services reported Wednesday.

The indictments, which have not been formally approved by the Turkish judiciary, could further strain relations between Turkey and Israel, which were once close but which deteriorated badly after the flotilla raid on May 31, 2010.

Israel has consistently rejected Turkey’s demand that it formally apologize for the commando raid and lift its blockade of Gaza.

Turkey’s semiofficial Anatolia news agency said the prosecutor, Mehmet Akif Ekinci, had prepared a 144-page indictment package that would seek life imprisonment for Gabi Ashkenazi, the former chief of general staff for the Israel Defense Forces; Vice Adm. Eliezer Marom, former commander of naval forces; Gen. Amos Yadlin, the former military intelligence chief; and Brig. Gen. Avishai Levy, the former head of air force intelligence.

The indictment further recommended that the four receive additional prison terms totaling 18,000 years for what it called other crimes committed by the Israeli side during the flotilla raid.

A six-vessel convoy, led by the passenger ship Mavi Marmara, sailing under the Turkish flag, was stopped by Israeli commandos in international waters as it headed toward Gaza with what activists described as emergency-relief cargo to help Gaza’s Palestinian population cope with an Israeli-imposed embargo.

Israel has asserted that it had the legal right to stop the activists from violating the embargo, which was intended to prevent shipments of weapons to Palestinian militants.

Eight of the activists killed were Turks; the ninth was an American of Turkish descent. A United Nations report on the raid released in September concluded that Israel had been within its legal rights but had used excessive and unreasonable force.

The Turkish indictment said the commandos were armed with rifles and other weapons, while the activists had “plastic flag masts, spoons and forks.”

The Israeli government had little to say Wednesday about the reports. “We’ve only heard about this from the media,” said Yigal Palmor, a Foreign Ministry spokesman. “We did not get any information or communications from the Turkish legal authorities, so we will not make any comment.”