A 12-year-old girl was assured firefighters were on their way to rescue her from Grenfell Tower as the child begged the 999 operator: "Please can you hurry up?"
Jessica Urbano Ramirez was one of the 72 people who died as a result of the blaze on June 14 last year.
She fled her flat on the 20th floor before taking refuge along with others higher up the 24-storey tower block, in west London.
Complaining of smoke and fire below, Jessica repeatedly asked London Fire Brigade control room officer Sarah Russell: "Please can you hurry up?"
Details of her 999 call, which lasted almost an hour, were revealed in a 70-page transcript at a public inquiry in central London on Monday.
At one point, Ms Russell, who had been in the job for about nine months by the time of the fire, said: "They are hurrying up. Is there another room you can go into?"
Jessica replied: "No, can you hurry up please? I'm begging you."
Ms Russell told her: "They are, they're right below you. But you need to keep yourself safe."
Giving evidence, the officer admitted she had no information that firefighters were on their way, but said she was trying to reassure the youngster.
Counsel to the inquiry Richard Millett QC asked her: "Did it occur to you that you had not yet assessed the security of the escape route and telling her that the crews were coming up, without having solid information to back that up, meant that you might be lulling her into a false sense of security?"
Ms Russell said: "At the time, no. It was based on what I would expect to happen, what should happen.
"It was more about comforting her and trying to get her through that situation and get the information (from her)."
Ms Russell said she would have liked to have had more experience in dealing with fire survival guidance (FSG) calls prior to the fire, having had just one day of FSG training eight or nine months earlier.
She also said it would have been helpful to have a more experienced control room officer sitting next to her.
In a written statement Ms Russell said she was glad she had stayed on the call "even if it was only to offer her a little support".
"After about an hour I could not get anymore response from her - only rasping sounds, then nothing," she said.
"I stayed on the line a little while longer with my hand hovered over the call termination button.
"I was torn as what best to do. I eventually ended the call when the line fell silent.
"Reflecting on that call, I felt completely helpless.
"When people are pleading with you, saying do not want to die and I cannot physically do anything to help them; it is very hard."
The information that Jessica had fled to a higher floor was not passed on to fire crews on the ground, who searched her flat but found no trace of the youngster.