Removing some children's heart surgery from Belfast could put lives at risk, campaigners have claimed.
Health minister Edwin Poots is considering the future of services for youngsters with congenital heart birth defects and some parents feared they could be sent to England for operations.
The Children's Heartbeat Trust wants an all-Ireland network operating between Dublin and Belfast to help ensure the viability of undertaking the specialised surgery locally.
Heartbeat Trust executive officer Sarah Quinlan said: "It is clear that any removal of surgery from Belfast would put at risk the lives of children born with critical congenital heart problems which are impossible to diagnose before birth.
"Also, the implications for other services, lack of 24/7 transport and the threat to the wider children's hospital mean that the future of this surgery must be secured through an all-island network operating between Dublin and Belfast and continued links with units in Britain."
Congenital heart disease is the most common birth defect in Northern Ireland, with around 250 babies born with the condition every year, according to the Heartbeat Trust.
Health Minister Edwin Poots is considering the future of services at the Royal Belfast Hospital for Sick Children amid concerns expressed by the Expert Panel Safe and Sustainable Report that surgery for children with congenital heart disease was not sustainable.
The issue has been debated in the Assembly with MLAs supporting keeping heart surgery locally.
Stormont public representatives were asked by the Children's Heartbeat Trust charity to sign a pledge to safeguard the future provision of congenital heart surgery in Northern Ireland on Monday. Ulster Unionist MLA Robin Swann penned the first signature at Stormont. His son Evan is only weeks old and awaiting treatment for the birth defect.
A health department spokesman said work was ongoing. "The minister is committed to the delivery of paediatric cardiac services which are safe and sustainable and which deliver the best outcomes for children," he added.