Russia and Egypt are working to resolve air security issues and resume operation of flights between the two countries, Kremlin spokesman Dmitry Peskov said Thursday. Moscow temporarily stopped all flights to Egypt after a Russian airliner carrying 224 passengers and crew members crashed over Egypt’s Sinai Peninsula region last October, killing all aboard.

“As for Egypt, you know that our special representatives are in contact with Egyptian colleagues. From the very beginning, when flights were suspended, we said that they were being suspended until the necessary security conditions for our [Russian] citizens were in place,” Peskov said, according to Sputnik News.

The comment comes a day after Russia’s Federal Air Transport Agency (Rosaviatsiya) said Wednesday it had sent recommendations on aviation safety to Cairo. Egypt officials said the implementation of the recommendations will take additional resources and time, Rosaviatsiya said, according to Tass news agency.

Meanwhile, Moscow’s flight ban might force some Russian airliners pull out of the market by late 2016, the air transport agency said Tuesday. About five or six airlines are likely to stop operating by October if Russia does not resume flights to Egypt — a popular tourist destination among Russians — by the summer, agency official Yury Malyshev said, according to Interfax news agency.

Although an investigation is ongoing to determine the cause of the Metrojet Flight 9268’s crash, Russian and Western governments said that the plane was brought down by a bomb — a theory consistently rejected by Egypt. In December, Cairo released a preliminary report saying its investigation committee did not "receive any evidence" that indicated foul play in the A321 Airbus’ crash.

In November, Britain said it had information that showed the plane was downed by an “explosive device.”  An American official had also said the same month that U.S. intelligence indicated the crash was most likely caused by a bomb planted by the Islamic State group or an affiliate of the militant group. Also in November, Russian newspaper Kommersant, citing an unnamed source, reported a bomb was placed in the aircraft’s main cabin.

Britain and Ireland have also suspended all flights to Egypt’s Red Sea resort of Sharm el-Sheikh, from where flight 9268 took off for Russia's St. Petersburg.