A toddler was in a life-threatening condition in hospital tonight after her bone marrow transplant was delayed by the growing volcanic ash cloud crisis.
The little girl, who cannot be named, was said to be in an "extremely vulnerable state" as flight restrictions were extended, preventing critical treatment arriving from a donor in Canada - her only hope of survival.
This evening she was being kept in isolation, the Anthony Nolan Trust said.
A spokesman for the organisation, which focuses on leukaemia and bone marrow transplantation, said the situation was "horrifically nerve-wracking" for the child's family.
"This really is a life or death situation. The transplant is her last chance of survival," the spokesman said.
The youngster is one of 16 patients now in "critical need" of treatment.
This number is likely to increase if the flight disruption continues.
Operations director Ailsa Ogilvie said volunteer couriers had been doing "everything humanly possible" to get transplants through using alternative means of transport.
"We have cells sitting in America while patients in the UK are being kept in isolation waiting for their transplant to arrive," she said.
"We've had volunteer couriers making epic train journeys across Europe in an effort to get cells to where they are needed in the fastest time possible."
But she said speed was imperative.
"Once the stem cells have been taken from the donor, there is a window of only about 72 hours for the transplant to take place before the cells die," she added.
"In addition, patients who are about to have their transplant are in an extremely vulnerable state as their immune system is effectively stripped away before they receive the new stem cells.
"They will be kept in isolation but this is obviously an extremely worrying time for all involved."
Sue Howard, who has been a volunteer courier for four years, said the past few days had been "very challenging".
Ms Howard, who is currently in Germany to pick up transplant material for a patient in Britain, said she managed to get the last seat on a Eurostar train out of London on Sunday morning before taking a connection from France to Frankfurt.
But her efforts almost came to nothing when she was told she would not be able to get on a return train to Paris tomorrow.
It was only after informing train managers that her journey was "a life or death situation" that she was able to secure a seat, travelling in first class.
"I was so worried - there is such a short space of time for the cells to get to the patient and if I hadn't been able to get on that train I don't know how else I would have made it," she said. "I was extremely relieved. The uncertainty is really difficult."
The Anthony Nolan Trust provides almost 900 transplants a year and regularly imports stem cells from bone marrow donors across the world.Reuse content