EgyptAir jet sent smoke-alarm warnings before crash

A spokesman for France's BEA air accident investigation agency said the signals did not indicate what caused the smoke or fire on board the plane, which plunged into the sea with 66 people on board as it was heading from Paris to Cairo.

But they offered the first clues as to what unfolded in the moments before the crash.

One aviation source said that a fire on board would likely have generated multiple warning signals, while a sudden explosion may not have generated any - though officials stress that no scenario, including explosion, is being ruled out.

Egypt said its navy had found human remains, wreckage and the personal belongings of passengers floating in the Mediterranean about 290 km (180 miles) north of Alexandria.

The army published pictures on May 21 on its official Facebook page of the recovered items, which included blue and white debris with EgyptAir markings, seat fabric with designs in the airline's colors, and a yellow lifejacket.

Analysis of the debris and recovery of the plane's twin flight recorders are likely to be key to determining the cause of the crash - the third blow since October to Egypt's travel industry, still reeling from political unrest following the 2011 uprising that ousted Hosni Mubarak.

Civil Aviation Minister Sherif Fathi told reporters an additional challenge in the hunt for the black boxes was the depth of the Mediterranean in the area under search.