The EgyptAir jet which crashed in the Mediterranean on Thursday reportedly sent a series of warnings indicating that smoke had been detected on board, shortly before it disappeared off radar screens.

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 crashed 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.

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 Saturday on its official Facebook page of the recovered items, which included blue and white debris with EgyptAir markings, seat fabric 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.

A suspected Islamic State bombing brought down a Russian airliner after it took off from Sharm el-Sheikh airport in late October, killing all 224 people on board, and an EgyptAir plane was hijacked in March by a man wearing a fake suicide belt.