At least 22 "possible serious untoward" incidents - three involving deaths - have been recorded in connection with the new NHS 111 advice line, it has been reported.
Two deaths are being investigated in the East Midlands, and one in the West Midlands, health magazine Pulse said.
A spokesman from Derbyshire Health United - which covers NHS 111 in Derbyshire, Nottinghamshire and Northamptonshire - said it was investigating the two deaths but so far it believes the system and processes that were followed would have been "exactly as expected".
NHS Direct - which covers eight NHS 111 areas - said it is investigating the unexpected death of a patient who was referred to a GP out-of-hours service in the West Midlands, Pulse reported
NHS England's board members have voted to set up a review into the service
More top news
A highly toxic chemical was used in the death of North Korean leader Kim Jong-un's half brother last week, tests have shown.
A new survey has highlighted the disconnect between people's views on the GB Olympic team and funding for grassroots sport.
National Crime Agency officers have arrested a British man in connection with bribery offences linked to international cricket spot-fixing.