Egyptian authorities have detained two employees of Sharm al-Sheikh airport for questioning in connection with the downing of a Russian jet on Oct 31 that killed all 224 people on board, two security officials and an airport employee said on Tuesday

"Seventeen people are being held, two of them are suspected of helping whoever planted the bomb on the plane at Sharm al-Sheikh airport," said one of the security officials who both declined to be named.

One of the security officials said CCTV footage showed a baggage handler carrying a suitcase from an airport building to another man, who was loading luggage onto the doomed airliner from beneath the plane on the runway.

An employee at the airport media department, who also preferred to remain anonymous, confirmed two members of the ground crew had been detained for questioning on Monday night.

The interior and civil aviation ministries' media departments denied in a statement that there had been any arrests.

Russia's FSB security service said on Tuesday it was certain a bomb had brought down the plane, joining Britain and the United States in reaching that conclusion.

Egypt has not yet confirmed that a bomb was responsible, saying it wants to wait until all investigations are complete.

It was not immediately clear what role the employees had at the airport, which is Egypt's third-busiest, handling a vast number of charter and budget flights for tourists seeking sea and sun in the southern Sinai peninsula.

Separately, other sources at the airport said security forces were searching for two employees who are suspected of leaving a baggage-scanning machine unattended for a period of time while passengers were boarding the doomed Russian plane.

CCTV footage was being examined to confirm what happened.

The sources said investigators had questioned all the airport staff involved with handling the Russian airplane, its passengers and bags after the crash.

No arrests had been made in the search for the two employees who were believed to have stepped away from the baggage-scanning machine.

Since the disaster, many flights to and from Sharm al-Sheikh have been suspended, raising concerns that Egypt's tourism industry, worth about $7 billion a year and still a pillar of the economy despite having fallen sharply in recent years, will be further ravaged.

Alexander Bortnikov, the head of Russia's FSB, said the conclusion of Russian investigators was that a homemade bomb containing around 1 kg (2 lbs) of TNT had detonated during the flight, causing the plane to break up in mid-air.

"We can unequivocally say it was a terrorist act," he said.

Egyptian ministers were meeting in Sharm al-Sheikh on Tuesday, with a news conference expected later in the day.