GPs have been told to stop performing most blood tests until mid-September, and hospitals to cut their number by 25%, as the NHS grapples with an acute shortage of sample bottles.

NHS England has ordered the unprecedented huge cut in blood testing because hospitals and GP surgeries have been hit with a severe and deepening shortage of the vials samples are put into.

The problem had already forced hospitals and GPs to start limiting the number of blood tests being carried out on patients.

But in new guidance issued on Thursday NHS England warned the shortage would get worse over the next few weeks and last for “a significant period”, which is believed may be months.

In the guidance letter it told GPs and hospital bosses that “the supply position remains constrained and is forecasted to become even more constrained over the coming weeks.

“While it is anticipated that the position will improve from the middle of September, overall supply is likely to remain challenging for a significant period.”

The organisation has managed to line up new, unidentified sources of supply for the plastic bottles, which are taken to laboratories for analysis. However, they will not be widely available for a while. “It will take time for these products to be imported and delivered in volume to services”, the letter added.

As a result “it is important and urgent that demand is reduced as much as possible”, so the NHS can cope with its increasingly limited supplies of the vials.

The shortage has arisen because Becton Dickinson, the NHS’s main supplier of blood collection tubes, has not been able to keep up with demand for its products.

A company spokesperson also cited other reasons. “In addition to increased demand, we are seeing continued transportation challenges that have affected all industries, including port and transport capacity, air freight capacity and UK border challenges. Suppliers are also challenged to meet increased demand for raw materials and components,” they said.

One GP described the action NHS bosses have decided to implement in the face of the worsening shortage as “drastic”. It poses a risk to patients because it could lead to delayed diagnosis of diseases and less monitoring of serious medical conditions, they warned.

The guidance in effect stops GPs and their staff from carrying out blood tests in all but the most urgent cases until 17 September. GPs are worried the ban could lead to cases of cancer, diabetes, heart problems and other diseases going undetected.

“All primary care and community testing must be halted until 17 September 2021, except for clinically urgent testing”, it said. The latter includes people with suspected cancer, blood tests that are very overdue or vital so that a patient can safely be prescribed certain medication, and people who may have sepsis or other conditions that carry a risk of disability or death.

“We appreciate that this temporary position is frustrating for patients and services alike,” said the letter. It was signed by Prof Stephen Powis, NHS England’s national medical director, Dr Nikita Kanani, its medical director for primary care, and Mark Cubbon, its interim chief operating officer.

Turning to hospitals, it adds that “acute and mental health trusts must reduce their demand by a minimum of 25% for the three-week period up to 17 September 2021”.

Some GP surgeries have stopped doing routine blood tests to assess the health of people with heart disease, high blood pressure and diabetes. In some places, GP practices have had to ring patients to tell them not to come in for pre-booked blood tests as a result of the problem.

The British Medical Association said doctors’ inability to order blood tests was “a huge concern” that would damage quality of care.

“Patients who need a range of blood tests may now face cancellations, or at best a delay with those tests and this is a huge concern,” said Dr David Wrigley, the BMA’s deputy chair.

“Blood tests are a fundamental part of patient care, giving us essential insights into different conditions, warning signs, and overall health. If they can’t be done or are delayed, then the quality of patient care is under threat.

“Clinicians across the NHS, in hospitals and GP surgeries, are getting increasingly concerned, and understandably asking what the plan is if they run out of blood tubes in the coming days and weeks.”

Doctors have been “left in an incredibly difficult situation, with no choice but to inform their patients that they cannot carry out certain blood tests for the time being and that appointments they may have for a test could be cancelled”, added Wrigley.