Thousands of 999 callers had the target time for an ambulance to reach them downgraded last year after first being classed as life-threatening emergencies.
Yorkshire Ambulance Service is facing new claims of target times being manipulated after it emerged that almost 11,000 emergency calls were downgraded in 2014.
Figures obtained by the Unite union show that 348 of the most serious “Red 1” calls were changed to less urgent “Red 2”.
Another 374 Red 1 calls were changed to “Green”, which requires a response time of between of up to 50 minutes or advice over the phone.
A total of 10,918 calls were downgraded in 2014, including 722 “Red 1” calls and 10,119 “Red 2” calls, according to figures released under freedom of information rules.
Ambulance bosses have insisted that response priorities are only changed when it is in the patient’s interest.
But Unite claims its members have warned that lives could be put at risk by the practice.
Len McCluskey, Unite general secretary, said: “What Unite has uncovered is absolutely alarming.
“There needs to be a thorough investigation into allegations that the service could be gambling with people’s lives.”
The practice of calls being downgraded by Yorkshire Ambulance Service emerged in August 2013, when it was claimed response times were being changed to meet targets.
At the time whistleblowers told the Express that calls were changed from “red” to “green” if a crew was not going to get to the patient within the eight-minute target time.
We also obtained documents which showed that a set procedure called “Clinical Triage of Red Calls” was used if it was likely targets would be breached.
If the 999 crew would not arrive in eight minutes, patients were transferred to a clinical adviser. The call was then downgraded to green if it was deemed not to be life-threatening.
But a review of the procedure by NHS bosses found it was safe. Yorkshire Ambulance Service pointed out that some calls were upgraded to “red” if the patient needed a more urgent response.
And an inspection by the Care Quality Commission (CQC) in July 2013 found that calls were only being re-triaged for clinical reasons and not to meet targets.
No harm to patients from calls being downgraded was found.
Unite has been locked in a bitter with the Yorkshire Ambulance Service NHS Trust since February 2013, when the union was de-recognised by bosses for negotiations on behalf of its members.
Trust bosses have accused Unite of making misleading claims about patient safety.
Responding to the latest figures, Ian Brandwood, the trust’s executive director of people and engagement said: “Their on-going campaign to try and discredit the organisation and the work of our highly-skilled and dedicated staff is purely about formal recognition at the trust and is not in the best interests of patients.
“Unite is consistently promoting sensational allegations without sharing their evidence. We have asked Unite on numerous occasions to raise their specific concerns with us and they have failed to do so.”