Health Minister Angela Smith said the attack was "deplorable"

About 40 youths went on the rampage at the casualty department of the Mater Hospital in the north of the city shortly after 2200 BST on Friday.

At the same time, a crowd gathered outside the hospital trying to gain entry.

Police were called to deal with the gang who had broken away from the Tour of the North parade earlier in the evening.

Ms Smith condemned the attack as disgusting and deplorable.

"It is disgusting and deplorable that such an incident should have infringed the sanctity of a hospital which is there to serve the entire community," she said.

I spoke to one of the very senior nurses who was on duty last night and he told me this was the most frightening thing he had seen Sean Donaghy Mater Chief Executive

"All responsible sections of the community will condemn it.

"I would like to praise the hospital for the way they dealt with the incident and for restoring normal services so quickly."

No-one was injured in the incident, however a hospital spokesman said the trouble caused great concern to both staff and patients.

Chief Executive of the Mater, Sean Donaghy, said the staff had never seen anything like it

"I spoke to one of the very senior nurses who was on duty last night, who has seen a lot through his 12 or 13 years with the Mater, and he told me this was the most frightening thing he had seen," he said.

"We have had some pretty challenging episodes so I think that speaks for itself.

"It really was very traumatic and we have had nothing like it prior to this."

Martin Morgan said patients shouldn't have to put up with such nonsense

Hundreds of Orangemen accompanied by bands took part in the parade which police said passed off without incident.

The County Grand Master of Belfast, Dawson Bailie, condemned what happened at the hospital.

"I totally deplore what took place after our parade last night at the Mater Hospital," he said.

"Those people who were involved in that we want nothing whatsoever to do with them."

A 15-year-old youth was arrested in connection with the disturbance, but was later released pending a police report.

Patricia McKeown, from the health union Unison, said what happened was disgraceful.

"It is thuggish elements who don't have the kind of respect for our health services or for people in need of treatment, and just believe they can behave in this way, who need to wise up," she said.

'Vulnerable target'

Local SDLP councillor Martin Morgan, who was monitoring the parade, described what happened as "unacceptable".

"People who are in the Mater Hospital seeking treatment for injuries or illness certainly shouldn't have to put up with the type of nonsense that went on last night," he said.

Sinn Fein assembly member Kathy Stanton also described the incident as unacceptable.

"In any society hospitals are treated with reverence and respect yet here we see loyalists taking advantage of a very easy and vulnerable target," she said.

Meanwhile, a loyal order parade from Whiterock Orange Hall has been banned from going along the Springfield Road in west Belfast next Saturday.

The Parades Commission determination has been criticised by unionists.

Nationalist residents had threatened a protest along the route if the Orangemen had been allowed through.