The first emergency aircraft carrying bodies of the crash victims arrived early Monday morning at St Petersburg's Pulkovo airport, where they were loaded onto stretchers and driven to the morgue to be identified. The next plane carrying the bodies of the remaining passengers is scheduled to depart Cairo for the airport later in the evening.

The Airbus A321 carrying 224 mostly Russian vacationers crashed in the Sinai Peninsula on Saturday morning, less than half an hour after taking off from a resort town on the Red Sea.

Egypt and several other countries are participating in a probe to determine the cause of the crash, which saw the plane reportedly break apart in mid-air as it set off for St. Petersburg.

'Too early to draw conclusions'

Shortly after the crash, a group affiliated with the "Islamic State" ("IS") claimed responsibility for the attack. Russian and Egyptian authorities are doubtful, however, saying the militants don't have weapons that could have downed a plane flying 9,000 meters (30,000 feet) feet in the air.

There has also been speculation that a pre-existing technical failure caused the crash, with one anonymous source at Sharm el-Sheikh airport telling DW that the plane had a history of technical problems.

Russian aviation commisioner Viktor Sorochenko said that in any case it was "too early to draw conclusions."

New concerns

Russian authorities sent over 100 emergency workers to Egypt to help recover the remains, as President Vladimir Putin declared a day of mourning that will last until Tuesday. Crowds of people gathered in St. Petersburg and Moscow to pay tribute to the victims.

Lufthansa, Air France and Emirates said they would halt flights over the Sinai Peninsula until the cause of the crash has been discovered. Meanwhile, concerns have been raised about Russia's poor air safety conditions, specifically those of smaller airlines like Kogalymavia, which was operating the flight.

Searchers are still locating the remains of all 224 victims. The black box from the crashed jet has been located, and investigators said its findings should be ready in a few days, AFP news agency reported.

blc/kms (Reuters, AFP, AP)