Loyalist paramilitaries have been accused of attacking and abusing staff inside Belfast's Royal Victoria Hospital.
The RUC is studying a video tape of an incident in the hospital casualty department in which a number of hospital staff were injured by people who claimed to be members of the Loyalist Volunteer Force.
The hospital said staff were physically assaulted, had their lives threatened and were spat upon.
Hospital medical director, Dr Ian Carson condemned the attacks and threats as deplorable.
He said: "Our personnel are drawn from all sections of the community and they provide vital services for that community.
"It is intolerable that people purporting to have interests in patients receiving crucial care, should subject staff to physical and verbal abuse and threaten their lives."
Dr Carson added: "This disgraceful behaviour must stop immediately and be condemned by all, especially those who would have influence in the group to which these people claim to belong."
The RUC confirmed they were carrying out an investigation in the trouble in the hospital which look place early on Saturday morning but which was only revealed tonight.
Meanwhile, a pipe bomb was defused outside a Catholic family home in Coleraine, Co Derry this morning. The RUC believe the device was thrown at the house during the night.
It is the latest in a long and growing series of sectarian attacks carried out by loyalist paramilitaries against the Catholic community.
The device was found on the doorstep of the Kylemore Road house and over 20 families were evacuated from their homes in the area while Army bomb disposal teams made the bomb safe.
The area was sealed off for over three hours.
The RUC issued an urgent appeal for people not to touch anything suspicious after it was revealed that a man visiting the family picked up the device before realising what it was.
The RUC said the fuse had been lit but it had burned itself out before the bomb exploded.
In January, another unexploded device was found at the house next door.
Elsewhere, a pipe bomb shattered a window and caused minor damage at the Glennock Chapel at Newtownstewart and a similar device was defused after being thrown at a Catholic home in Coleraine.
Police believe the attacks happened during the night, the latest in a long and growing series of sectarian attacks carried out by loyalist paramilitaries.
The attack on the Co Tyrone church was only discovered when worshippers arrived for Sunday morning service.
In Armagh pipe bomb was defused after being found stored in the roof space of a flat in Gough Avenue. There were no arrests.