A statement from Immanuel College – a private Jewish school in Hertfordshire – widely reported in the UK press said her family had “asked that we all keep them in our thoughts and prayers during this extremely difficult time”.
It added: “We are all praying for a miracle for Charlotte and the others.”
Crans-Montana’s tourism website also lists her as a babysitter in the resort during school holidays.
The bar that was the scene of the fire, Le Constellation in the resort of Crans-Montana, was full of Swiss people and tourists celebrating New Year’s Day in the early hours of Thursday when the blaze began in the basement area.
Prosecutors say that, according to initial investigations, the likely cause of the fire was sparklers on champagne bottles being carried “too close to the ceiling”.
Switzerland’s President Guy Parmelin called it “one of the worst tragedies” experienced by the country.
An investigation into the causes of the blaze will focus on the materials used at the site, the bar’s fire safety measures, its capacity and the number of people inside at the time, Valais Attorney General Beatrice Pilloud said.
It could take days if not weeks to identify the victims of the fire, Swiss authorities said.
Officials said 113 of the injured had been identified, with authorities still working to identify the other six.