Thousands of Russian tourists were returning home from Egypt on Sunday, as suspicions mount that a bomb may have caused the crash of a St. Petersburg-bound charter jet over the Sinai on Oct. 31.
"Today is the busiest day in this sense," Russian Deputy Prime Minister Arkady Dvorkovich said Sunday.
Russia announced Friday it was suspending flights to Egypt until it determined the cause of the crash, which killed 224 people.
"Until we know the real reasons for what happened, I consider it expedient to stop Russian flights to Egypt," said Alexander Bortnikov, the head of the Russian security service the FSB.
"Above all, this concerns tourist routes."
Planes were sent to the country to retrieve Russian tourists. Egypt is a major tourist destination for Russians, and about 80,000 were still in the country as of Saturday, mainly in Sharm el-Sheikh and Hurghada. Several European countries, including Britain, also briefly suspended flights to the country.
More than a week after the crash, speculation has increasingly centered around the possibility that a bomb was responsible.
The head of the crash investigation, Ayman el-Muqadem, said Saturday that a noise is heard on the plane's black box, occurring in the last instant before the plane went down.
The Wall Street Journal reported that there is no evidence of mechanical failure on the tape:
"The cockpit recorder hasn't revealed any pilot discussion of mechanical or system problems before the midair breakup, according to two people familiar with the thinking of some of the investigators."
But el-Muqadem insisted that the black box tape didn't necessarily indicate a bomb and that "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."
He also said foreign agencies had not shared any intelligence with Egypt that confirmed the existence of a bomb.
But western officials sound more and more convinced of a bomb. Rep. Michael McCaul, R-Texas, the chairman of the House Homeland Security Committee, told Fox News Sunday the sound on the black box was evidence of a bomb:
"When you couple that with the satellite technology, this flash of heat on the airplane, the fact that ISIS has declared war on Russia, this was a Russian plane headed for Russia, in addition to the U.S. and U.K. intelligence that we have received, I think all indicators are pointing to the fact that this was ISIS putting a bomb on an airplane."
Phillip Hammond, British Foreign Secretary, said Sunday his government believes it is "more likely than not" that an explosive device brought down the plane.
The Wall Street Journal reported that Egypt's internal security agency has been questioning workers at Sharm el-Sheikh airport, a sign it believes insiders might have played a role in the crash.
The Egyptian branch of Islamic State claimed responsibility for the crash hours after it happened and repeated its claim days later.
Russia also said Sunday it is sending experts to inspect security at Egypt's airports.