The RUC chief constable said tonight it was too early to say who was responsible for yesterday's gun attacks in North Belfast.
Sir Ronnie Flanagan spoke out following unionist calls for a Government review of the IRA cease-fire following a gun attack on a police patrol and another on a Protestant home.
But he said what had been witnessed in recent days were "acts of terrorism".
"Paramilitaries are involved but at this stage it is too soon for us to say exactly which paramilitary organisations are involved because there are a whole range of possibilities."
He said there was no doubt that members of the loyalist Ulster Defence Association had been involved in the ongoing sectarian violence. But it was a matter for Northern Ireland Secretary Dr John Reid to decide whether there should be a declaration by him that the UDA cease-fire was over.
Dr Reid is already keeping the UDA cease-fire under review and Sir Ronnie, speaking to journalists after an international policing conference in County Antrim, said the organisation's violence "ebbed and flowed".
He said there seemed to have been a decision to desist when the Secretary of State warned some weeks ago that he was watching the UDA "then there seemed to be a decision to reengage".
"I have no doubt there is ample evidence that members of the UDA have been engaged in acts of terrorism, no doubt of that whatsoever."
He was certain it was a UDA member who threw the blast bomb which seriously injured one of his officers earlier this month during the loyalist protest mounted against Catholic primary school children being taken to class.
Sir Ronnie today held a series of top level meetings to discuss the North Belfast situation as the RUC admitted it was getting increasingly harder to police the growing sectarian clashes.
Sir Ronnie said: "It is desperately difficult to police North Belfast. My officers are injected between the two communities to prevent violence being heaped by one upon the other and, as so often is the case, each community directs their violence at my officers.
"It is utterly unacceptable and anybody with any influence should exercise that influence to bring it to a stop."
The ultimate solution was neither a policing one nor a security one, he said.
"It is in the hands of the community. They must look at this and realise it is the communities right across the board who suffer," he said.
PA