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
Feeling colder with a biting, bitter windchill
A thoughtful teenager has taken Valentine's romance to a whole new level by buying 900 flowers and giving one to every girl in his school.
The group of Adelie penguins dwindled from 160,000 to 10,000 after an iceberg got stuck near their colony, scientists have found.