France's BEA crash investigation agency held a meeting behind closed doors with the relatives of last year's Germanwings crash victims in Barcelona on Saturday.

According to The Associated Press news agency, the investigators told the relatives that the doctors who were treating Andreas Lubitz - who deliberately crashed the plane into a French mountainside last year - had refused to divulge details about the co-pilots mental health situation.

The German doctors were not required to disclose information about their patients under German privacy laws, the officials told relatives.

"They (the investigators) emphasized that the doctors, those who treated him, refused to give any information," said Robert Tansill Oliver, whose 37-year-old son Robert Oliver Calvo had died in the crash.

Lubitz, the co-pilot of Germanwings flight 9525, flying from Barcelona to Düsseldorf, had previously been treated for depression. The crash killed all 150 people on board.

The BEA report about the crash is set to be released on Sunday, and it is expected it will make recommendations to help aviation agencies and airlines prevent similar crashes.

Germanwings and its parent company Lufthansa have repeatedly denied any wrongdoing in the crash, insisting that Lubitz was declared fit to fly the plane.

However, the investigations have revealed that Lubitz had visited 41 doctors in the months before the crash, and none of them warned the Germanwings administration that he had depression issues. A similar meeting to that in Barcelona was held in the western German city of Bonn, for relatives of the German victims.

Relatives were 'really upset'

Christof Wellens, a lawyer for some victims' families, said it was very important for the relatives to understand why Lubitz decided to killed so many people along with him.

"Everyone in the auditorium was asking the same question: 'Why did these German doctors refuse to talk to you?" said Oliver, adding that he feared that the truth about Lubitz' situation might never come out.

"How did he fall through the cracks? The controls did not work," he said, suggesting that Germany needed to change its privacy laws.

"People were not happy at all with some of the explanations. Some of the family members felt as if these BEA representatives were Lubitz' lawyers – making excuses as to why Germanwings didn't take action knowing what they knew," the victim's father added.

shs/ rc (AP,dpa)