Russia has dismissed any theories about what caused the Russian plane to crash in Egypt's Sinai Peninsula as "speculation" after British and US officials said a bomb may have brought down the plane.
Dmitry Peskov, Kremlin spokesperson, said on Thursday that only the official investigation can determine what happened.
He said "any other proposed explanations seem like unverified information or some sort of speculation".
Peskov also said Russian planes were continuing to fly to and from the Red Sea resort of Sharm el-Sheikh, despite Ireland and Britain suspending flights.
His comments came a day after Philip Hammond, UK foreign secretary, said that there was a "significant possibility" the crash was caused by a bomb.
After a meeting on Wednesday of the British government's crisis committee, COBRA, Hammond said Britain was advising its citizens not to go on vacation to Sharm el-Sheikh, which is visited by hundreds of thousands of Britons a year.
Intercepted communications played a role in the tentative conclusion that the Islamic State of Iraq and the Levant (ISIL) group's Sinai affiliate planted an explosive device on the plane, a US official briefed on the matter told Associated Press news agency.
The US and British security sources, however, stressed they had reached no final conclusions about the crash, as forensic evidence from the blast site, including the airplane's black box, was still being analysed.
Meanwhile, Russian and Egyptian investigators said that the cockpit voice recorder of the Metrojet Airbus A321-200 had suffered substantial damage in the weekend crash that killed 224 people.
Information from the flight data recorder has been successfully copied and handed over to investigators, the Russians said.
ISIL, which controls expanses of Iraq and Syria and is battling the Egyptian army in the Sinai Peninsula, said again on Wednesday it brought down the airplane.
- The Sinai armed group that claimed responsibility for the crash calls itself Sinai Province.
- It pledged its allegiance to ISIL in November 2014.
- The group focuses its attacks on Egyptian security forces.
- It's been active in the Sinai since 2011, and was originally known as Ansar Beit Al-Maqdis.
- In July, it killed at least 70 members of Egypt's security forces in a series of attacks.
Russia began on Thursday to bury the first victims of the crash as several hundred people gathered in the the city of Veliky Novgorod, around 200km south of Saint Petersburg, to bid farewell to Nina Lushchenko, a 60-year-old school employee.
Friends and relatives at the funeral said they did not want to assign blame and would like to steer clear of politics.
Remarks earlier on Wednesday by David Cameron, UK prime minister, of concerns "the plane may well have been brought down by an explosive device" drew criticism from Sameh Shoukry, Egypt's foreign minister.
He told CNN he was "somewhat surprised" by the British statement.
"This is a matter for the investigation to clarify and we should not prejudge or take any measures that might have implications," Shoukry said.
A Russian aviation source told the Reuters news agency that the investigation into the crash is looking into the possibility of an object stowed on board causing the disaster.
"There are two versions now under consideration: something stowed inside [the plane] and a technical fault," the source said.
"But the airplane could not just break apart in the air - there should be some action. A rocket is unlikely as there are no signs of that."
Hammond's remarks came as Britain prepared to host a visit by Egyptian President Abdel Fattah el-Sisi this week.
Egypt, a close ally of the US and the most populous Arab country, dismissed a similar claim of responsibility for the crash by ISIL on Saturday.
Blow to tourism
The ISIL affiliate in the Sinai says it downed the plane because of Russia's recent military intervention in Syria.
Both Egypt and Russia have dismissed the claim of responsibility, with the Egyptian president calling it "propaganda".
The suspension of flights is a further blow to Egypt's troubled tourism industry, which has suffered in the unrest that followed the 2011 Arab Spring.
Several airlines, including Lufthansa and Air France, stopped flying over Sinai after the crash.
The Irish Aviation Authority followed the British lead and directed Irish airlines to suspend flights to Sharm el-Sheikh Airport and into the airspace of the Sinai Peninsula "until further notice".