Video report by ITV News Political Correspondent Daniel Hewitt
A delivery of 84 tonnes of desperately needed personal protective equipment for front line NHS staff as they treat patients with coronavirus has been delayed.
The shipment - including 400,000 gowns - was due to arrive in the UK from Turkey on Sunday afternoon.
The Royal Air Force (RAF) is on standby to bring the equipment on Monday, the Government announced.
It is not known what caused the delay.
The supplies have been described as “critical” by NHS Providers, which represents hospital trusts.
The eagerly anticipated supplies were due as hospital staff and NHS Providers said they feared they would run out of vital PPE this weekend.
NHS Trusts across the country have warned they face shortages of gowns, masks, gloves and other protective equipment which is designed to keep staff treating Covid-19 patients safe.
The critical shortage is of full-length protective clinical gowns.
Health bosses said the shipment would provide only enough PPE to last "a few days".
Niall Dickson, chief executive of the NHS Confederation, said it "may be enough to avert an absolute crisis over this weekend" but "it doesn't solve the longer term problem".
Responding to the delay, Mr Dickson said: "This is very serious and makes a difficult situation worse.
"It would have been better had the Government not made the announcement in the first place - we know shipments in this supply chain are unreliable and even when they do arrive they are not always what is expected.
"In future, the NHS will expect announcements when supplies have arrived not promises about what may or may not be delivered."
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He said it is likely some hospitals will now run out of gowns but added: "Everything that can be done will be done to protect patients and staff.
"We understand there are other potential sources of supply but - to be clear - nothing is guaranteed.
"There was already a loss of confidence and real anxiety across the NHS and care system around PPE supply - this will have been further eroded by what has happened this weekend.
"It will not be restored until we have a stable supply chain and certainty that staff will be given what they need when they need it.
"At the moment we are a long way from that point."
It comes after the Hospital Consultants and Specialists Association (HCSA) said officials responsible for the UK's "disgraceful" lack of adequate personal protective equipment need to be held "fully accountable for their abject failure" to protect front-line health staff.
HCSA president Claudia Paoloni said: "Our NHS workers are going above and beyond on a daily basis to heal.
"They should expect at the very least adequate protection to keep them fit and well to engage in this fight.
"Yet instead they are being asked to sacrifice themselves due to the failings of others."
The Government has been under fire for weeks over the distribution of PPE, with some front-line staff warning they have to work in situations where they feel unsafe.
One doctor who spoke to ITV News said the lack of protective equipment has left them feeling like “lambs to the slaughter”.
Dr Asif Munaf on shortages of PPE in hospital
Dr Asif Munaf, an NHS consultant in the East Midlands, told ITV News: “Every day the fear gets more and more.
"Especially with 50 colleagues being admitted to ITU and 20 colleagues dying in the past few weeks...
"I never thought I’d be in a developed country, a first world country, wearing plastic aprons...
“I’m scared for my family going home.
"I’ve got a two-year-old son.”
Dr Munaf said staff at his hospital were already having to ration PPE.
“It’s very limited.
"We’re having to ration this quite heavily."
He added he was making sure "my toilet break is limited, my prayer break is limited", in order to reduce the number of times he had to change his PPE.
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“These things are part of the premium.
"They should be single basic use, but they’re not.
"We’re having to wear them for multiple patients.”
Dr Munaf added many doctors currently felt "like lambs to the slaughter".
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Dr Chaand Nagpaul, chairman of the British Medical Association (BMA) council, said he had written to the Government two weeks ago calling for a massive ramping up of the manufacturing of protective equipment.
He said large numbers of contacts were willing to produce equipment and names of around 70 of them were passed on to the Government.
But Dr Nagpaul said the contacts "hit a brick wall" after they were not followed up.
He told Sky News: "We made it clear weeks ago that we need to do something about the likelihood of a lack of protective equipment."
When Cabinet minister Gavin Williamson was asked why the government has not responded to manufacturers who are willing to produce PPE, he said they will be contacted in the next 24 hours.
Speaking at the government's daily coronavirus briefing, he said a billion extra PPE have been brought into the country while the Government was doing "immense work" in trying to find British suppliers.
He encouraged those suppliers who have been in contact with the Government and have "slipped through the net" to get in touch again.
He said the Government will ensure they are contacted "in the next 24 hours".
He added: "We recognise this is a national endeavour and we are so incredibly grateful for so many people who are willing to step forward to make a real difference, and we certainly don't want to miss out on those opportunities."
Speaking alongside Mr Williamson was Deputy Chief Medical Officer Dr Jenny Harries, who said there should have been a "more adult, and more detailed conversation about PPE supplies".
She continued "it is important to remember that, although there may be elements of distribution problems across the UK at different times and in different places, this is a huge pull on services which we have never seen before".
Dr Harries added that part of the issues with getting adequate supplies of PPE was "that even though when orders go in overseas, supplies may be very different what is received to what we think we're going to get".
She added that PPE supplies would be allocated to "whichever patient or whichever healthcare worker at highest risk across the UK requires" them.
Dr Harries was also questioned over the changing government guidance on PPE that healthcare workers should reuse gowns or wear different kit where possible, such as plastic aprons with coveralls, if stocks run low in England.
Asked if she would be comfortable treating Covid-19 patients by re-using single-use PPE, Dr Harries said: "If I happened to be working on the frontline today I have a responsibility to look after patients to the best of my ability, to protect my colleagues and my staff and to manage my practice safely".
Dr Harries added that due to a "global shortage... we all need to use this PPE carefully.
"Some sessional use is entirely appropriate.
"For example wearing a gown for sessional use with a disposable plastic apron on top of it is an entirely appropriate use of PPE."
Unions representing doctors and nurses have expressed concerns about the change in guidance, saying it puts frontline workers at risk, but the Department for Health says the changes to PPE guidance is designed to help staff know what they should wear if such shortages become apparent.
Also on Sunday, the government's early response to the coronavirus crisis came under heavy criticism in a wide-ranging Sunday Times report which detailed how Boris Johnson missed five meetings of the government's key Cobra committee as the health crisis was gathering pace.
Reports in the Sunday Times also claimed the government missed a series of opportunities to try and lessen the impact of the outbreak in February and March.
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