In a new twist possibly aimed at appeasing the Turks, Syria’s information minister, Omran al-Zoubi, was quoted as telling a private Turkish broadcaster on Wednesday that Syrian antiaircraft gunners might have mistaken the Turkish plane for an Israeli one. “Turkish planes and Israel planes look like each other,” he was quoted as saying by the broadcaster, A Haber.

In the struggle to find a diplomatic solution to Syria’s turmoil, Kofi Annan, the special envoy to Syria for the United Nations and the Arab League, said he would convene a ministerial-level meeting on Saturday in Geneva involving what he has called countries of influence in the conflict. Mr. Annan’s peace plan has been paralyzed since he announced it more than two months ago,

Participants in the meeting would include the five permanent members of the Security Council — China, France, Russia, Britain and the United States — and emissaries from the European Union, the Arab League and Turkey. But the list of invitees conspicuously omitted Iran, Syria’s most important regional ally, which Mr. Annan had wanted to include. The United States and its allies objected strongly to Iran’s participation, contending that Iran aids the Syrian leader’s harsh repression of the 16-month-old uprising against him.

The conflicting accounts of who assaulted the television station, Al Ikhbaria, a satellite broadcaster, reflected the difficulties that outsiders face in determining the true course of events in the Syrian conflict, from which independent reporters and most international relief and monitoring officials are effectively barred.

Those difficulties were illustrated Wednesday in findings by a panel from the United Nations Human Rights Council in Geneva, which is investigating rights violations in Syria but has been blocked from conducting the inquiry inside Syria and has relied heavily on testimony from refugees and defectors. The panel said that it was unable to determine conclusively who was responsible for the May 25 massacre of 108 civilians in Houla, a string of villages in western Syria, but that it “considers that forces loyal to the government may have been responsible for many of the deaths.”