Men were handcuffed at the scene by police
Members of the Provisional IRA kidnapped a prominent dissident republican in Belfast, the chief constable has said.
Bobby Tohill was found injured in a van which was stopped by police officers in Castle Street, in the city centre, shortly before 1800 GMT on Friday.
Four other men, who were also in the van, were arrested during the extensive security operation.
Two more people were arrested on Saturday.
It is not clear what kind of injuries Mr Tohill sustained, but he is said to be in a stable condition in hospital.
Chief Constable Hugh Orde, who met senior officers to discuss the matter, said he had no doubt who was behind the kidnapping.
"The activity last night was Provisional IRA activity, I'm clear on that," he said.
"I'm also clear, as we have said quite recently, that the punishment beatings that go on in republican areas are also carried out by the Provisional IRA."
Huge Orde said Provisional IRA was behind kidnapping
He added: "What we're talking about was an operation last night by uniformed officers from a local police station, who arrested people who we would say are connected to the Provisional IRA."
The police said no shots were fired at or from within the van.
BBC Northern Ireland security editor Brian Rowan said the chief constable had made it clear that decisions on ceasefires were not a matter for him.
"But in the past 24 hours he has pointed to continuing paramilitary violence on both sides," he said.
"Yesterday he linked the UDA to murder, beatings, drugs and other criminal activities and now he has put the IRA inside the frame in connection with yesterday's abduction."
The Northern Ireland Office said the incident was an "example of the kind of behaviour the prime minister has described as completely unacceptable, and paramilitary behaviour of any kind must come to an end."
In a statement, Sinn Fein said details of the incident were not clear.
It added: "Sinn Fein's position on this kind of activity is very clear. We have
consistently opposed it and will continue to do so."
Ulster Unionist leader David Trimble said the incident "underlines the on-going problem of paramilitarism in society".
A van was stopped in Belfast city centre
He added: "The republican political leadership needs to make it clear as to where it stands and where the republican movement as a whole stands on such activity."
SDLP Assembly member for West Belfast Alex Attwood said: "All criminal activity and violence must end, and be seen to end."
"All violence must stop. There is no basis for a private army and we all need to see this," he said.
The DUP's Ian Paisley junior said Northern Ireland Secretary Paul Murphy must shut Sinn Fein out of the political process.
He said: "Sinn Fein/IRA are calling to be included in the government of Northern Ireland and yet it appears that the PIRA are engaged in terrorist activities."
BBC Ireland correspondent Denis Murray said: "This comes at a time when the republican movement says it's holding up its end of the peace process.
"But it demonstrates that it's still highly active as an organised illegal army."
The Millfield area was completely closed to traffic during the security operation, from the junction at Peters Hill with North Street to Divis Street.
Part of Bank Street was also cordoned off as police carried out follow-up searches.