Activists greet the Mavi Marmara upon return to Istanbul, Dec. 2010, (Reuters).
United Nations spokesman Martin Nesirky gave no specific date for the much-delayed report, which Israeli officials said on Sunday was now expected on 20 August, a Saturday.
UN officials had originally suggested the report by a four-man inquiry panel could be finalised in February, then April and most recently, in late July.
Asked about the latest statements by Israeli officials, Nesirky told reporters: "The members of the flotilla panel agreed to delay finalizing the report until later in the month of August." He gave no reason for the delay.
The UN report on the May 2010 Israeli raid on the Mavi Marmara as it tried to breach the blockade on the Gaza Strip at the head of an aid flotilla has become a headache for Israel, which has been resisting Turkish demands for an apology.
Turkey, which like Israel had a delegate on the UN inquiry panel led by former New Zealand prime minister Geoffrey Palmer, has yet to sign the report and envoys of Israeli Prime Minster Benjamin Netanyahu have been in bilateral talks with Ankara in hopes of bridging their rifts on the issue.
The Israeli military came under fierce criticism for the May 2010 raid, which led to a severe deterioration of its ties with Turkey.
The United Nations has urged Israel to end the blockade. But Israel says the blockade prevents arms from reaching the territory's ruling Hamas Islamists, who are hostile to the Jewish state.