Ambulance delays are feared to have caused up to 81 patient deaths at a trust judged to be in "crisis", a former health minister has said.
Norman Lamb said he had seen a list of 40 cases of potential patient harm linked to response time delays at the East of England Ambulance Service Trust (EEAST), including 19 cases where patients had lost their lives.
But he added he understood there were a further 120 incidents of potential patient harm, and the death total could exceed 80.
Mr Lamb also voiced concerns of complacency about the trust's leadership, despite the Care Quality Commission telling him the service is "in crisis" and that "patients are at risk".
He said he had "deep concerns" about any person across the East of England getting the service they need "in their hour of need".
Senior staff also drive Jaguars, Range Rovers, Mercedes and Audi A5s while there have been recruitment difficulties, Mr Lamb added.
For the Government, health minister Steve Barclay said "a wide-ranging plan of immediate actions has been put in place to address the issues that were identified" following a "risk summit".
The EEAST also defended itself via a series of tweets during the debate, saying it was unable to respond to a "very small number" of the 50,000 calls it handled over a 15-day period "as quickly as we would like".
It said it was "thoroughly investigating" them.
Concerns about EEAST were raised in the Commons last month by Labour's Clive Lewis (Norwich South), who raised allegations of people dying due to ambulances arriving late over a 12-day period where the service had failed to move into its highest state of emergency.
Speaking during an adjournment debate, Mr Lamb said: "Beyond the list of 40 cases, I understand there's a further 120 incidents of potential patient harm associated with delays.
"We're talking potentially about up to 81 patient deaths over this period of time associated with delays."
The North Norfolk MP raised cases of patients having to wait longer than expected for help, including a woman who died after suffering a stroke and a heart attack.
He went on: "I'm told the assessment of many internally is that the service over this period of time was unsafe and that they don't have assurances that going forward, if there was a period of very cold weather or a flu epidemic, that the trust would be able to provide a safe service."
Mr Lamb said there had been "several occasions" during this period where more than 200 calls via 999 could not be responded to at the moment they came in as "there were no crews or ambulances available".
He added: "I have deep concerns about any family member of mine, any constituent or anyone else across the East of England who has to rely on this service that they will get a service that will protect them and safeguard them in their hour of need."
Mr Barclay said he had spoken to the chief executives of NHS England and NHS Improvement, and also the chairman of the risk summit, about the issues.
He went on: "I am also assured that the trust has identified all potential causes where there were serious delays in response, and following an initial investigation it is examining 22 such cases through the serious incident procedure.
"This will ensure that individual cases are properly investigated."
The EEAST said: "The trust was unable to respond to a very small number of the 50,000 calls we handled over a 15-day period as quickly as we would like. We are thoroughly investigating these and working with families to keep them updated.
"Every year, demand on the service goes up. The trust was prepared for winter. However, the festive period was unprecedented, with extreme levels of demand and delays in handing patients over at hospitals. At peak demand times, a 999 call was received every 20 seconds."
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