Egyptian investigators have arrested two airport staff employed at the Sharm-al-Sheikh airport on suspicion of helping the Isis plant a bomb on a Russian passenger plane, which caused it to blow up mid-air, killing all 224 passengers on board. 

According to Russian news agency, Sputnik, the two detained airport staff were on duty on the day the Kagalymavia flight blew up mid-air.

A security officer said that 17 people are being held by Egyptian security agencies.

"Seventeen people are being held, two of them are suspected of helping whoever planted the bomb on the plane at Sharm al-Sheikh airport," a security officer was quoted as saying by Reuters.

Egyptian authorities have not yet confirmed the arrests. The development has come as Russia formally confirmed that the plane crash in Egypt's Sinai Province was a terrorist attack. The Islamic State (Isis) terrorists had taken responsibility for blowing up the plane.

Russian Federal Security Service (FSB) chief Alexander Bortnikov told TASS on Tuesday that a homemade explosive equivalent of up to one kg of TNT was placed on the plane that caused it to explode and break mid-air, killing mostly Russians flying to St Petersburg after vacationing at the Sharm el-Sheikh resort.