A six-year-old boy has been left in a critical condition after he was reportedly shut outside by his parents in freezing temperatures over Christmas.

The boy’s French mother, 31, and Belgian stepfather, 21, face charges of torture after forcing their son to stay on their balcony for 15 hours as punishment for helping himself to food from the fridge.

The unnamed boy was found unconscious and suffering from hypothermia when emergency services were called to a flat in Saint-Josse in Brussels on Boxing Day evening.

His twin sister was also taken to hospital for treatment, local news sources reported.

A statement from the Belgian prosecutor’s office said both children showed signs of malnutrition and abuse.

According to Belgian media, the boy had been forced out onto the balcony at around 5am on Boxing Day and stayed outside in temperatures below 3 degrees Celsius until around 8pm.

A prosecutor’s office statement said: “The step-father has confessed without realising the seriousness of the facts, while the mother is still in denial.”

The boy was said to still be in a “very critical condition in hospital” and both parents were being held in police custody, Het Laatste Nieuws reported.

According to the Dutch-language Belgian news website, the children’s mother said she was asleep all day and blamed her partner for the abuse.

The balcony the boy had been shut out on was said to be at the back of the apartment building, and not visible from the street – which local media said helped explain why no-one had raised concerns sooner.

Local authorities said the children were not registered at any school in the city.