Russia has announced it will suspend all flights to Egypt until security is improved at its airports.

It is the first sign of wariness from Moscow after days of resisting British and American warnings that a bomb may have brought down a Russian plane in the Sinai Peninsula last week.

The suspension is a heavy blow to Egypt's vital tourism industry.

Russian tourists fleeing the cold to flock to Egypt's beach resorts have helped keep tourism alive after it collapsed across much of the country in the past five years of turmoil.

Moscow's move will also strand 30,000 to 40,000 Russians currently in Egypt, even as the British government struggled to bring home some 20,000 of its nationals stuck there after it halted flights earlier in the week.

Metrojet's Airbus A321-200 crashed 23 minutes after take-off from Sharm el-Sheikh on Saturday, killing all 224 people on board, mostly Russians.

While the US and Britain have stopped short of a categorical assignment of blame, Prime Minister David Cameron said on Thursday it was "more likely than not" that the cause was a bomb - a claim dismissed as premature by the Russians and Egyptians.

Still, on Friday, the head of Russian intelligence, Alexander Bortnikov, recommended a suspension.

"I think it will be reasonable to suspend all Russian flights to Egypt until we determine the real reasons of what happened," he said. "It concerns tourist flights most of all."

President Vladimir Putin quickly agreed. His spokesman Dmitry Peskov said the suspension would last "until when a proper level of aviation security is in place", denying it would go on until the investigation was completed.

Asked whether the suspension means that Russia now views terrorism as the main theory, Mr Peskov said: "It definitely doesn't mean that. Not a single theory can be given priority since there aren't any definite indications to prove it."

Wreckage from the plane has been brought to Moscow to be tested for any possible traces of explosives, according to emergency situations minister Vladimir Puchkov. The samples came "from all parts where traces of explosives could be", he said.

A US official briefed on the Metrojet crash said earlier that intercepted communications by Islamic militants in the Sinai played a role in the tentative conclusion that Islamic State's (IS) Sinai affiliate had planted an explosive on the flight.

While Russia still underlined that no conclusion had been reached, it joined Britain in demanding stricter security measures at Egyptian airports. Britain on Wednesday grounded all flights to and from Egypt's Sinai Peninsula.

Russia's suspension went even further, covering all destinations in Egypt. Egypt maintains there is nothing wrong with the Sharm el-Sheikh airport, the main entry to Sinai beach resorts.

London approved the resumption of British flights to Sinai starting on Friday but imposed heavier security measures, particularly a ban on checking in baggage. But the result snarled efforts to bring back the hundreds of British tourists waiting at Sharm el-Sheikh airport to return home. Baggage left behind because of the ban was piling up and overwhelming the airport storage, Egypt's civil aviation minister, Hossam Kamal, said.

"This big volume will affect the smooth operation of the rest of the domestic and international flights," said Kamal, adding that a cargo plane would carry bags separately for each flight.

As a result, Egypt was limiting the number of British flights coming to pick up the tourists, reducing them to eight on Friday instead of the planned 29, he said.

Tempers ran high among the crowds of British tourists in the airport departure lounge. When UK ambassador John Casson appeared to reassure them, one British tourist who had waited at the airport since early morning hours, harangued him with angry shouts of: "When are we going home?"

British carrier EasyJet had been due to operate 10 flights from the Red Sea resort but said eight would not be able to fly because Egypt had suspended them.

Mr Casson, the ambassador, tried to reassure the tourists, saying that British authorities will "continue to work until we have everybody home".

"There are challenging, difficult issues to work through, this is a busy airport and we need to make sure people leave in a way that is safe," he said.

Meanwhile Dutch carrier KLM allowed its passengers leaving at Cairo airport to only take hand luggage for a flight on Friday. A statement on KLM's website said the measure is "based on national and international information and out of precaution".

As a result, only 115 of the 247 passengers booked on the plane took the flight on Friday, with the rest refusing to leave without their check-in bags, security officials at the Cairo airport said.

Air France said that it is reinforcing screening in Cairo and monitoring the situation with Egyptian authorities. France's foreign ministry has urged its citizens to avoid Sharm el-Sheikh and also the Sinai resort of Taba as well as surrounding areas, unless they have an "imperative reason" to go.

IS has claimed responsibility for bringing down the plane, but Russian and Egyptian officials say the claim was not credible. Russia is conducting an air war in Syria against IS militants who have promised retaliation.

Several flights heading to Sharm el-Sheikh to bring back stranded British tourists turned around in mid-air, and airlines are scaling back the number of flights they plan to operate.

Monarch sent five empty planes from Britain to the Red Sea resort but said only two would return on Friday. Two more were on the ground in Sharm el-Sheikh and the fifth was diverted to Larnaca, Cyprus.

Thomas Cook said only one of its four planes due in Sharm el-Sheikh to pick up tourists was being allowed to land. Flight-tracking websites showed two turning back mid-flight.