SHARM EL-SHEIKH, Egypt (AP) -- A noise was heard in the last second of the cockpit voice recording from the Russian plane that crashed last week in Egypt's Sinai, killing all 224 people onboard, the head of the Egyptian investigation team said Saturday.

Ayman el-Muqadem told a news conference in Cairo that an analysis of the noise was underway to identify its nature. He said the way the debris was scattered over a wide area indicated the Airbus A321-200 broke up mid-air, but initial observations don't shed light on what caused it.

U.S. and British officials have cited intelligence reports as indicating that the Russian flight from the Sinai resort town of Sharm el-Sheikh to St. Petersburg was brought down on Oct. 31 by a bomb on board.

Also Saturday, Egypt's foreign minister complained that Western governments had not sufficiently helped Egypt in its war on terrorism and had not shared relevant intelligence with Cairo.

Sameh Shoukry, speaking at a press conference, said that "European countries did not give us the cooperation we are hoping for."

Egypt's past calls for assistance and coordination on terrorism issues from "the countries that are now facing the danger" had not been dealt with seriously, he said.

Shoukry also complained that Western nations that have suspended flights to Sharm el-Sheikh did not share with Cairo the relevant intelligence upon which they based their decisions.

Shoukry told reporters that Egypt "expected that the information available would be communicated to us instead of being broadcast" in the media.

The foreign minister's comments came as Egypt launched an investigation into the staff and ground crew at the Sharm el-Sheikh airport, according to Egyptian airport and security officials.

The officials told The Associated Press on Saturday that authorities were questioning airport staff and ground crew who worked on the Russian flight and had placed some employees under surveillance. The officials all spoke on condition of anonymity because they were not authorized to speak to the media.

The crash one week ago dealt another blow to Egypt's battered tourism sector, which is yet to fully recover from years of political turmoil. Russians comprise nearly a third of all tourists who visited Egypt in the past year.

Islamic State extremists have claimed that they brought down the Russian Metrojet flight, with mostly Russian tourists onboard, though they did not offer any proof.

Egyptian authorities have been trying to whip up support for a war on terror after the military overthrow of Islamist President Mohammed Morsi in 2013. A crackdown on Islamists and a series of militant attacks on security buildings and checkpoints, mainly in the restive Sinai Peninsula, have followed Morsi's ouster - with a Sinai-based affiliate of the Islamic State group claiming responsibility for some of the most devastating attacks.