The mother of two young brothers found dead in her car during this week's French heatwave took them swimming to cool off and then to a supermarket before returning home to unpack the shopping - and forgot they were in the vehicle, her family has admitted.

In a tragedy that has sent shockwaves through France, four-year-old Kassim Benouali, and his younger brother Sadek, two, died from a cardiac arrest around ten minutes after they were left in the car.

The boys were found unresponsive in the back of her car parked in direct sunlight on the drive of their grandmother's home in the Bois de l'Ubac area of Carpentras, southern France on Monday.

Neighbours heard the screams of their devastated mother Wafa El Boubkari, 33, who discovered their bodies.   

Fatiha, the boys' grandmother told the Daily Mail: 'It's a tragedy. It was really, really hot on Monday. It was a terrible heatwave. So, my daughter Wafa took the boys to the swimming pool in the morning and then did some shopping.

'She then drove home with the boys who she left in the car to offload the shopping. May Allah have mercy on their souls.'

She went on: 'The media have been saying horrible things about my family and trying to make out that something suspicious has taken place. It was a genuine mistake, nothing illegal has happened. Everybody has been struggling to focus in this heat, she got busy, and my daughter was also dealing with a lot of other things in her life.'

The boys' funeral took place on Friday amid emotional scenes. Mourners first gathered for prayers at Carpentras Mosque before making their way to a local cemetery where the brothers were buried together.

But their heartbroken grandmother's account of what took place appears to contradict what Ms Boubkari has told police who are investigating the deaths.

She initially claimed that she left them in the back of the car after returning from shopping with them and then became busy as she unpacked the groceries, causing her to 'forget' about the boys.

But she now insists that the children climbed into the back of the car without her knowledge and that it locked automatically behind them, meaning that they could not get out. 

She said that she was in the house during this time getting on with everyday chores.

Ms Boubkari, who has two other children aged under ten, faces charges of unintentional manslaughter.

If found guilty of such a charge, defendants face up to 15 years in prison, and 20 if there are aggravating circumstances.  

In a further twist to the mystery of what led to the deaths, friends and family have also claimed that she had recently split from her husband and had been under huge emotional pressure.

She only moved into her mother's home with her four children around six months ago after her marriage ran into problems and was being helped to care for them by members of her extended family.

Ms Boubkari's sister, who did not want to be named, said: 'We are still trying to understand what happened and this is a very difficult time for us all. Wafa hasn't stopped crying, she's in a bad way, she's barely able to speak.

'She had been going through a lot of personal difficulties, things haven't been easy for her lately. What happened to her boys is a big tragedy and we are all doing our best to help her.'

A friend revealed: 'Wafa had only been at her mother's house with her children for a few months. She didn't live very far away in Carpentras with her husband, but I don't know if her split from him was a permanent thing.

'Who knows? She may have been distracted by all the other things going on in her life.'

Her two sons died in the car when the outside temperature was 48C with investigators claiming that it may have been as high as 70C inside the vehicle without any air conditioning on.

Ms Boubkari first took her children to the local swimming pool, located around two miles from her home to help them cool down as temperatures soared. 

After around an hour, they then left and stopped to buy groceries at the Grand Frais supermarket, before driving home, which took around 15 minutes.

She discovered the boys in her white Peugeot at around 1pm when they were in cardiac arrest. Emergency services were unable to resuscitate them, and they died on the driveway as Ms Boubkari and other family members looked on.   

A neighbour said: 'It's hard to know how this could have happened because from what I saw, there was quite a bit of time between her returning home and the children being discovered.

'They're very young children and even though it's quite a large house, how could you not know where they are for such a long time? Hopefully, the investigation will be able to get to the bottom of all this.'  

A preliminary postmortem conducted on Tuesday found that the boys died of dehydration from 'exposure to excessive heat.'

Ms Boubkari spent the early part of this week in hospital with shock while her mother and other family members have been staying at another location in Carpentras, with the five bedroom home in a cul-de-sac where the tragedy took place empty. 

Ms Boubkari worked in La Maison Jounaud in the centre of Carpentras, a patisserie that specialises in making artisanal chocolate and has branches all over the south of France.

It has been run for three generations by the same family and is one of the best-known patisseries in the region.

One of her colleagues revealed that she had been working there serving customers for around five years.

She added: 'We are waiting to speak with Wafa but have sent our condolences to her and the family. She's a very nice, hardworking, down to earth woman who was dealing with a lot of things.

'She's a very good mother and was doing her best. The pain she is going through must be unimaginable and beyond words. Our hearts go out to her, what has happened is horrific and tragic.'

The ⁠double tragedy occurred as temperatures soared across France and the rest of Western Europe, driven by a mass of hot air moving north from the Sahara, fuelled by a strong high‑pressure ​system known as the 'African anticyclone'.

Meteorologists say the system is creating a so‑called 'heat dome', trapping hot air over western and central Europe, and ​allowing temperatures to build day after day.

Another French child died in similar circumstances in France on Wednesday afternoon, after being locked in the family car in Saint-Gratien, north of Paris.  

The three-year-old, who has not been named, was 'found by his parents in the vehicle parked in front of the home,' said a local police spokesman.

And it emerged yesterday that a fourth child, this time an an 18-month-old baby had died in a car in France after being fortgotten by a parent.

The infant was discovered unconscious in a car parked at the Aix-Marseille University medical campus on Monday.

On Tuesday, France registered its hottest day on record at 44.3C while the average nighttime temperature is around 30C, another record high for the country.

The intense heat saw two of Paris's landmarks - the Louvre and the Eiffel Tower - close earlier than usual.

A spokesperson for the Louvre said the building was 'not sufficiently adapted to climate change.'

Around 40 people across the country were also confirmed to have drowned during the unprecedented heatwave while swimming in unsupervised areas.