The changes, to take effect from 2018, will be announced in a speech to a global summit on patient safety in London later this week.
UK health secretary Jeremy Hunt told the 'Guardian' newspaper that the second doctor will be unconnected with the patient's treatment, in a move intended to improve care and help bereaved relatives understand why their loved one died.
"Expert medical examiners will sign off on all hospital deaths, which means that all deaths are getting a second look. They can go into real detail about cases they have real worry about and report that to the trust," Hunt said.
"But part of their role will be to look at trends and if there's been a sudden increase in people dying, they might spot a trend there," he said.
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The doctors will report any concerns to the relevant National Health Service (NHS) trust or potentially the Care Quality Commission. From 2018 doctors acting as expert medical examiners will review and confirm the cause of all the 250,000 deaths a year that occur in hospital.
Peter Walsh, chief executive of the Action against Medical Accidents patient safety charity in the UK, backed the "much overdue" move.
He said: "We desperately need to see serious improvement in the capacity of NHS investigations to get to the bottom of patient safety incidents and bring about real improvements in patient safety.