Cairo - Egyptian President Abdel-Fattah el-Sisi on Wednesday vowed to enhance security in the country amid suspicions that a bomb caused the crash of a Russian passenger airliner in Sinai more than a week ago."We will make more efforts in order to ensure security and safety for each visitor to Egypt," al-Sisi said, according to the official Middle east News Agency.He called for Egyptians' unity at what he described as "this hard time.""No one can break the will of Egyptians," al-Sisi said during a tour of the Sinai resort city of Sharm el-Sheikh.The Metrojet flight crashed on October 31 shortly after departing from Sharm el-Sheikh en route to the Russian city of St Petersburg, killing all the 224 people on board. Almost all the victims were Russian.The tragedy prompted Russia and Britain to halt flights to Egypt, triggering fears about potential impact on the Egyptian tourism, a main source of the national income. Suspension of the flights is estimated to cost Egypt around $281m a month, Egyptian Tourism Minister Hesham Zazou said on Wednesday.Commercial flight ban"The losses may reach LE6.6 billion if the suspension lasts for three months," Zazou said following a cabinet meeting on the consequences of the plane crash.Tourists from Britain and Russia account for around 66 % of the tourist traffic in Sharm el-Sheikh, according to Zazou.On Tuesday, Kremlin's chief of staff Sergei Ivanov said that Russia's ban on commercial flights to Egypt might last at least several months.British and US officials have suggested that the plane had been downed by a bomb. Egypt has repeatedly warned it is too early to determine the cause.An affiliate of the Islamic State terrorist group active in Sinai claimed responsibility for the crash, which is the deadliest civil aviation disaster in Russian history.Even before the jet crash, Egypt's tourism industry was in the doldrums due to the unrest, which has gripped the country since the 2011 uprising that forced longtime autocrat Hosny Mubarak out of power.