CAIRO -- A noise was heard in the last second of the cockpit voice recording from the Russian plane that crashed Oct. 31 in Egypt's Sinai Peninsula, the head of the joint investigation team said Saturday, bolstering U.S. and British suspicions the plane was brought down by a bomb.

Ayman el-Muqadem warned, however, it was too early to say what caused the plane to apparently break up in mid-flight. Analysis of the noise was underway.

"All scenarios are being considered. ... It could be lithium batteries in the luggage of one of the passengers, it could be an explosion in the fuel tank, it could be fatigue in the body of the aircraft, it could be the explosion of something," said El-Muqadem, who is Egyptian and leading the investigation committee that includes experts from Russia, France, Germany and Ireland, where the plane was registered.

U.S. and British officials have cited intelligence reports as indicating the Oct. 31 flight from the Sinai resort town of Sharm el-Sheikh to St. Petersburg was brought down by a bomb on board. All 224 people onboard, most of them Russian tourists, were killed.

Islamic State extremists claimed they brought down the Metrojet flight, without offering proof, saying it was in retaliation for Moscow's airstrikes that began a month earlier against fighters in Syria.

El-Muqadem said debris was found scattered across an eight-mile stretch of desert, indicating the Airbus A321-200 broke up mid-air, but initial observations don't shed light on what caused it. Some pieces of wreckage still were missing, while the recovered pieces will be taken to Cairo for analysis, he said.

Egyptian airport and security officials said Saturday authorities were questioning airport staff and ground crew who worked on the plane 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.

Also Saturday, Egypt's foreign minister complained Western governments had not sufficiently helped Egypt in its war on terrorism.

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, Sameh Shoukry said. "European countries did not give us the cooperation we are hoping for," he said.

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 Sinai Peninsula, followed Morsi's ouster -- with a Sinai-based affiliate of the Islamic State group claiming responsibility for some of the most devastating attacks.

Shoukry also said countries that have suspended flights to Sharm el-Sheikh -- which include the U.K. and Russia, though the foreign minister did not specifically name them -- did not share the intelligence that drove their decisions with Cairo.

Egypt "expected that the information available would be communicated to us instead of being broadcast" in the media, he said.

Russia announced Friday it was suspending flights to all of Egypt, joining the UK and Ireland, which had stopped flights to Sharm el-Sheikh. At least a half-dozen Western European governments told their citizens not to travel there. Empty charter planes have been flying to Sharm el-Sheikh to bring home stranded Russian and British tourists. Passengers were banned from checking in luggage -- reflecting an apparent concern about security and luggage-screening procedures at the airport.

The crash one week ago dealt a huge 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.

There are 80,000 Russians in Egypt -- 79,000 of them in the resort areas of Hurgada and Sharm el-Sheikh, Russian tourism chief Oleg Safonov was cited as saying by Russian news agencies.

Maya Lomidze, acting director of the Russian Association of Tour Operators, said authorities were sending 93 empty planes to Egypt on Saturday and Sunday to bring tourists home. The Russian Emergencies Ministry also said it would send planes to transport the checked baggage of Russian tourists who were forced to leave their suitcases behind.

Thousands of tourists waited in slow-moving security lines at the Sharm el-Sheikh airport on Saturday as they tried to board charter flights home. Many complained about a lack of information from travel agents and airlines, but seemed to accept tight security measures.

Designer Georgy Kononov and his family hoped to catch a flight to Moscow after a seven-hour delay. He said he agreed with Russia's decision to suspend flights to Egypt.

"When we're talking about the safety and security of people, it's more important than the business," he said, though he added that there should have been better planning for such a complicated situation.

Meanwhile, British media on Saturday reported more troubling news for the Egyptian tourism industry, saying a plane carrying British tourists narrowly missed being hit by an Egyptian missile on Aug. 23. The British government and Thomson Airways confirmed the incident.

The Guardian and other British media said a rocket came within 1,000 feet (300 meters) of a Thomson jet bound for Sharm el-Sheikh with 189 passengers.

The British Department for Transport said its investigation concluded it was not a "targeted attack" and likely connected to routine Egyptian military exercises in the area at the time. Thomson said there was "no cause for concern" for further flights.