Hisham Kahlfallah had once again made the round of hospitals and he was exhausted when he turned up outside the victims’ centre in Nice. His sister Olfa was dead and her four-year-old son Kylan had been listed as missing. He could get no further details from the authorities about the little boy. Four days after the massacre on the promenade in Nice, just 35 out of 84 bodies of the victims had been identified.

Bereaved families are increasingly venting their frustrations at the authorities. When Christian Estrosi, the head of the regional council, turned up for an official visit at the centre on Sunday, Mr Kahlfallah could no longer contain himself.

“Christian, come to us, why are you not coming this way? We have questions for you, you call the media but you don’t call the families of the victims. What about our dead?” he said.

Mr Estrosi strode away, but an aide spoke to Mr Kahlfallah, explaining that the office of the public prosecutor was refusing to release the list until all checks had been concluded.

Kylan’s father, Tahar Majri, was outside the Pasteur Hospital where he thought he might find his son. “I have done everything, I have been to police stations, hospitals, tried Facebook. My wife is dead, where is my son? Bye, bye Kylan if I don’t see you again," he said, weeping.

Yannick Favre was also at the hospital, in search of his friend Jeanne, who has not been seen since the night of the attack.

“What happened was so bad; but this is a form of torture, not knowing, hoping she was at worst injured but not dead, but also fearing to hope,” he said, shaking his head. “It is really unacceptable that we are not getting this information, really unacceptable.”

The mood of anger and frustration, with the government seemingly impotent to prevent repeated terrorist attacks in the country, was shown today when the prime minister, Manuel Valls and other ministers arrived at the city’s Monument du Centenaire for a minute's silence in remembrance of the victims. Resounding jeers and boos were directed at them by the crowd. Many accuse the government of not having enough police on duty during the Bastille Day celebrations despite an ongoing threat.

The French authorities say they are doing what they can about the identification of the bodies. An accelerated procedure established after the Isis murders in Paris last November, using DNA and family medical records, is in place but they stress that it is impossible to give a definite timeframe.

France attack: Mourners pay respects in Nice

“This process is step by step, so that everything is guaranteed the moment that the identities are established and released," said health minister Marisol Touraine. She added that up to a dozen more of the dead would be identified soon.

According to hospital staff one of the problems with identification is the horrific injuries inflicted by 31-year-old Lahouaiej Bouhlal’s 19-tonne refrigerated truck, especially on the young boys and girls he mowed down. Ten of those killed were children, as were 54 of the injured, the youngest a six-month-old baby.

But many feel that the authorities are not doing enough. An American student from Berkeley, Abhinav Kukreja, was distributing flyers outside the city’s central police station seeking the whereabouts of three friends who had been studying with him at the European Innovation Academy in Nice.

“The police weren’t helping us at all. We had made multiple calls, so we decided to bring out these flyers,” said Mr Kukreja. “The American embassy told us it was OK to go ahead, but the police are apparently unhappy that we are doing this.”

In pictures: Bastille Day Nice attack Show all 30 1 /30 In pictures: Bastille Day Nice attack In pictures: Bastille Day Nice attack A man reacts near bouquets of flowers near the scene where a truck ran into a crowd at high speed killing scores and injuring more who were celebrating the Bastille Day national holiday in Nice Reuters In pictures: Bastille Day Nice attack A woman arrives with a toy and a bouquet of flowers as people pay tribute near the scene where a truck ran into a crowd in Nice Reuters In pictures: Bastille Day Nice attack A woman reacts as she places flowers in front of the memorial set on the 'Promenade des Anglais' where the truck crashed into the crowd during the Bastille Day celebrations in Nice EPA In pictures: Bastille Day Nice attack People gather to view the floral tributes near the site of the truck attack in the French resort city of Nice AP In pictures: Bastille Day Nice attack A man reacts near bouquets of flowers as people pay tribute near the scene where a truck ran into a crowd at high speed killing scores and injuring more who were celebrating the Bastille Day national holiday, in Nice Reuters In pictures: Bastille Day Nice attack Floral tributes are laid out near the site of the truck attack in the French resort city of Nice AP In pictures: Bastille Day Nice attack A child's toy is placed among the floral tributes laid out near the site of the truck attack in the French resort city of Nice AP In pictures: Bastille Day Nice attack Investigators continue at the scene near the heavy truck that ran into a crowd at high speed killing scores who were celebrating the Bastille Day in Nice Reuters In pictures: Bastille Day Nice attack Crime scene investigators work on the 'Promenade des Anglais' after the truck crashed into the crowd during the Bastille Day celebrations in Nice EPA In pictures: Bastille Day Nice attack A forensic expert examines dead bodies covered with a blue sheet on the Promenade des Anglais seafront in the French Riviera city of Nice Getty Images In pictures: Bastille Day Nice attack A forensic expert evacuates a dead body on the Promenade des Anglais seafront in the French Riviera city of Nice, after a gunman smashed a truck into a crowd of revellers celebrating Bastille Day Getty Images In pictures: Bastille Day Nice attack A man reacts as he sits near a French flag along the beachfront the day after a truck ran into a crowd at high speed killing scores celebrating the Bastille Day in Nice Reuters In pictures: Bastille Day Nice attack Discarded items are left on the beach, not far from the site of the truck attack in the French resort city of Nice AP In pictures: Bastille Day Nice attack Bullet holes in the windscreen of the lorry that was driven into the crowd at high speed Reuters In pictures: Bastille Day Nice attack A man walks through debris on the street in Nice, France, the morning after a lorry ran into a crowd, killing at least 84 and injuring 50 Reuters In pictures: Bastille Day Nice attack Rescue workers help an injured woman to get in a ambulance AFP/Getty Images In pictures: Bastille Day Nice attack Authorities investigate a truck after it plowed through Bastille Day revelers in the French resort city of Nice, France AP In pictures: Bastille Day Nice attack Celebrations of Bastille Day were targeted by the lorry driver AP In pictures: Bastille Day Nice attack People cross the street with their hands on thier heads as a French soldier secures the area after at least 84 people were killed along the Promenade des Anglais in Nice Reuters In pictures: Bastille Day Nice attack A paramedic attends one of the dozens of people injured in the Nice Bastille Day attack In pictures: Bastille Day Nice attack Soldiers march on street where the lorry crashed into the crowd REUTERS In pictures: Bastille Day Nice attack A man sits next to a body seen on the ground after at least 84 people were killed in Nice, when a truck ran into a crowd celebrating the Bastille Day national holiday Reuters In pictures: Bastille Day Nice attack Bodies are seen on the ground after at least 84 people were killed in Nice, when a truck ran into a crowd celebrating the Bastille Day national holiday Reuters In pictures: Bastille Day Nice attack Children were among the 84 killed in the atrocity, with around 50 more hospitalised Reuters In pictures: Bastille Day Nice attack French Interior Minister Bernard Cazeneuve (2nd L) speaks to the media in Nice AFP/Getty Images In pictures: Bastille Day Nice attack A man walks with his hands up as police officers carry out checks on people in the centre of French Riviera town of Nice AFP/Getty Images In pictures: Bastille Day Nice attack With injured people laying in the street police and onlookers react near to a truck in Nice AP In pictures: Bastille Day Nice attack Police officers, firefighters and rescue workers are seen at the site of the attack AFP/Getty Images In pictures: Bastille Day Nice attack Police officers speak with a soldier after a truck that ploughed into a crowd leaving a fireworks display in the French Riviera town of Nice AFP/Getty Images In pictures: Bastille Day Nice attack Police shine a light into the cab as they approach the driver's cab of a truck, in Nice AP

One of the friends Mr Kukreja was searching for, 20-year-old Nicolas Leslie, a fellow Berkeley student from San Diego, has in fact been declared dead by the French authorities to the FBI. But Misha Bazelevsky, a 22-year-old Canadian, and 21-year-old Rickard Krussberg, from Estonia, remain missing.

Relations of 12 of those killed were allowed to see the bodies of the victims for the first time on Sunday, when the authorities issued the first death certificates and also the first permission for funerals. Some of the families waiting anxiously had been Muslims whose religion requires burials to take place within 24 hours whenever possible.

The Sahroui family, originally from Algeria, were among those who went to see their dead on Sunday. They had lost a three-year-old girl and an eight-year-old boy, their mother and an uncle. Among those who went to the morgue to carry out a final identification was the children’s sister, a young teenager.

A woman reacts to the news of the death of her grandson in Nice (Getty Images)

A volunteer counsellor at the victims centre, Yasmin Toauabia, said: "As you can imagine, they are in a state of shock.

"The grandmother kept repeating that her pain was not being able to bury them, the wait. They could at least have been buried right away if they had died at home.”

Brigitte Erbibou, a psychologist who has been working with survivors of the attack, described the reaction of two children whose father had been killed and whose mother is missing.

“The more the days go by, the more they suspect that the death announcement will come”, said Ms Erbibou. “ However, until it is announced, the wait is so difficult because there is no way to come to terms and begin the grieving process. That is what the children are telling me, they say 'with our Dad we know, but with our mum, it’s unbearable'.”