The breaching of the 4 million barrier for the first time since the waiting time target was introduced in August 2007 will raise fresh questions about the government’s stewardship of the health service. Critics will seize on it as evidence that Theresa May is giving the NHS too little money to help it cope with an unprecedented rise in demand for healthcare.

NHS England said on Thursday that 3.83 million people were on the waiting list for non-urgent hospital care in July, a slight increase on 3.81 million in June. However, it admitted that once estimates were factored in for how many patients were waiting at six hospital trusts that did not submit data for the referral to treatment (RTT) scheme, the total had gone over 4 million.

In a statement it said: “Factoring in estimates based on the latest data submitted for each missing trust suggests the total number of RTT patients waiting to start treatment at the end of June 2017 may have been just over 4.0 million patients.”

Under RTT patients should wait no longer than 18 weeks after being referred for planned care in hospital, usually an operation, often non-urgent such as a hernia repair or hip or knee replacement.

The six trusts that submitted either no data or only partial data to NHS England statisticians were Barts in London, the NHS’s biggest trust, which has five hospitals; Gloucestershire hospitals trust; Northern Devon; the Royal Orthopaedic hospital in north-west London; St George’s trust in south London; and Calderdale and Huddersfield NHS foundation trust.

Opposition parties and health trade unions are likely to claim that the breaching of the 4 million barrier is an embarrassment for the government and proof that it is doing too little to help hospitals, many of which have been struggling for several years.

Labour introduced the 18-week waiting time target in a bid to stop patients waiting unduly long for surgery. In the first month figures for it were produced, in August 2007, the total number was 4.187 million. It went down rapidly to over 3 million, then fell to over 2 million. However, it hit 3 million again in April 2014 and began creeping up towards 4 million from mid-2016. It was 3.67 million in January, 3.78 million in April and 3.81 million a month later.

Although the total of just over 4 million is not unprecedented, it is a moment that ministers have been quietly dreading, and NHS bosses have been expecting, for some months.

It follows the controversial decision of the NHS England chief executive, Simon Stevens, in March to relax the requirement for hospitals to treat at least 92% of patients on the RTT waiting list within 18 weeks, which the Royal College of Surgeons and other medical groups said would leave patients waiting longer in pain and anxiety for their procedure.

NHS experts said the waiting list rising above 4 million illustrated the depth of the crisis facing hospitals and that the service can no longer meet many of its own key waiting times.

“This shocking figure is another damning indictment of the crisis we are experiencing in the NHS and is another example of how every unresolved problem impacts on another area,” said Dr Mark Holland, the president of the Society for Acute Medicine.

“It is a fact that the NHS has less beds than other health economies and it is a fact that we have a workforce crisis. We need these problems to be addressed and to do this we need a proper strategic plan. I anticipate that today we will hear the usual defence rhetoric when the truth is that one of the richest nations on the planet is consistently failing to deliver care in line with its own standard,” he added.

NHS experts said the waiting list rising above 4 million illustrated the depth of the crisis facing hospitals and that the service can no longer meet many of its own key waiting times.

“This shocking figure is another damning indictment of the crisis we are experiencing in the NHS and is another example of how every unresolved problem impacts on another area,” said Dr Mark Holland, the president of the Society for Acute Medicine.

“It is a fact that the NHS has less beds than other health economies and it is a fact that we have a workforce crisis. We need these problems to be addressed and to do this we need a proper strategic plan. I anticipate that today we will hear the usual defence rhetoric when the truth is that one of the richest nations on the planet is consistently failing to deliver care in line with its own standard,” he added.