No theories ruled out on EgyptAir crash after smoke report: Paris

"At this time... all theories are being examined and none is favoured," he told a news conference after meeting with around 100 relatives of passengers who were aboard the doomed A320 that left Paris early Thursday for Cairo with 66 people aboard.

"The reports circulating here and there, which by the way are sometimes contradictory, give rise too often to nearly definitive conclusions," Ayrault said, warning of the "painful tension" caused to the families of the victims.

"Finding the plane is of course the priority, along with finding the black boxes to analyse them, which will allow us to answer legitimate questions," he said, referring to the voice and flight data recorders.

READ: 'Smoke on board' EgyptAir plane before crash

France's "dual goal" is to offer "solidarity with the families but also transparency... on the circumstances of this plane's disappearance," said the foreign minister, who was joined by Egypt's ambassador to France at the meeting with the family members.

"I strongly emphasised the desire of the French authorities to tell the entire truth about what happened," he said. "It's a legitimate and essential expectation for all the families."

The meeting took place "in a climate of intense emotion and great dignity," Ayrault added.

Crash investigators briefed the relatives on what is known so far and the procedures for establishing the cause.

"Methods and procedures for identifying the victims" were also explained to the families, Ayrault said.

The passengers included 30 Egyptians, 15 French citizens, two Iraqis, two Canadians, and citizens from Algeria, Belgium, Britain, Chad, Portugal, Saudi Arabia and Sudan. They included a boy and two babies.