A&E waiting time targets in England have been missed every month for two years, new figures show.
The NHS managed to admit, transfer or discharge 90.3% of patients from A&E in four hours or less in July.
However, the National Health Service has not achieved its 95% target since July 2015.
A total of 3.83 million people were also on waiting lists in June this year, figures revealed, the highest level since December 2007.
The NHS Confederation has described the current system as "unsustainable", calling for further transformation and investment.
Figures released on Thursday showed there were 500,498 emergency admissions in July 2017 - only the third time since records began that emergency admissions in a month have topped half a million.
An NHS England spokesman said nine out of 10 patients were being admitted, treated, and transferred or discharged from A&E within four hours, which was "up on the May 2017 performance".
But the NHS Confederation, representing health organisations in England and NHS Employers, has called for significant investment.
Deputy chief executive Danny Mortimer said: "Performance against these targets shows the system is under pressure and needs transformation and investment.
"(Politicians) should be more willing to fund health and social care, more supportive of radical change, more prepared to back services not buildings and more courageous in supporting new models of care that bring about better outcomes for patients."
In the first six months of 2017, an average of 369,007 patients waited longer than 18 weeks to start treatment after being referred by their GP.
The average figure for the same period in 2016 was 289,195, while in 2015 it was 208,489.
The NHS estimates the total number of patients on waiting lists for treatment at the end of June 2017 may have been slightly more than four million, as five trusts did not submit the relevant figures.
Labour leader Jeremy Corbyn has said NHS patients can not "afford another year of Theresa May".