Bristol Children's Hospital is being investigated after concerns were raised by three couples whose children died there.
The Sunday Express reported yesterday that the families claim their children - all heart patients - died following neglect.
One of the couples who have spoken out are Tiffany White and James Willcox, from Gloucester, who allege neglect in the case of their son Oscar who died in April at nine weeks.
The Citizen told the family's heartbreaking story last month.
According to the Sunday Express, a fourth family says poor treatment led to their son's brain damage.
It is understood that the hospital will scrutinise its last 50 child heart deaths.
These allegations follow the Bristol heart scandal in the 1980s and 1990s - when at least 35 babies died.
The Sunday Express reports that three of the families have begun legal action against the hospital trust and government watchdog the Care Quality Commission has launched an investigation.
The other children involved are seven-year-old Luke Jenkins, from Cardiff, and Sean Turner, four, from Warminster, Wiltshire, who had the same heart operation last spring.
According to the Express, both died with their parents believing they lacked adequate medical and nursing care.
Jack Casey, now three, from Bridgend, South Wales, nearly died when surgeons pierced his lung lining in March 2010, leaving him with brain damage.
University Hospitals Bristol Trust said: "It is important to stress how complex the needs of these children are. Incidents do occur in a complex speciality such as paediatric cardiac services where we are caring for some of the sickest children in the region.
"Each incident, no matter how minor it may appear, is recorded, rigorously investigated and actions taken forward as part of our clinical governance process."
