Dissident republicans are being blamed for an attack on the vice-chairman of the Policing Board in Londonderry.
Denis Bradley is in a stable condition in hospital
Denis Bradley sustained a head injury after being attacked with a baseball bat as he watched a football match in a bar. He was not seriously injured.
Chief Superintendent Richard Russell said: "Our major line of inquiry has to be that dissident republicans were behind this particular attack."
It has been condemned by unionist and nationalist politicians.
Mr Bradley was with his son in the Leckey Road bar, in the Brandywell area, when he was attacked by a hooded man at about 2200 BST on Tuesday. He is in a stable condition in hospital.
Chief Superintendent Russell said police would be looking into previous attacks on Mr Bradley, which include a petrol bomb attack on his home and death threats.
Referring to the latest incident, he added: "It doesn't seem to have been a random attack, although it may well have been an opportunistic attack."
Mr Bradley is being kept in hospital for observation for a second night on Wednesday.
Sir Desmond Rea, chairman of the Policing Board - which holds the PSNI to account - said he was shocked and appalled by the "vicious" attack.
"I am sure that I speak on behalf of every member of the board and its staff in roundly condemning this totally unwarranted attack," he added.
Northern Ireland Secretary Peter Hain also condemned the attack.
He said he had contacted Mr Bradley's wife Mary by telephone.
"I told her we all stand shoulder-to-shoulder with Denis in his refusal to be cowed by thuggery and violence, which must be rooted out and dealt with wherever it comes from."
The attack took place inside a Londonderry bar
SDLP leader Mark Durkan visited Mr Bradley in hospital and said he "managed to appear composed" despite his injuries.
He added that Mr Bradley was attacked with a cut-down baseball bat.
"It was a vicious and appalling attack on a man who is simply showing public service and community leadership and who can argue his views clearly," he said.
"He is a man who can take the views of others and explain and justify his actions - none of which can be said of his attackers."
Sinn Fein's Martin McGuinness, who also visited Mr Bradley in hospital, said the attack was "wrong and unacceptable".
"The fact that he is the vice-chairperson of the Policing Board does not warrant an attack on either him or his family.
"I am glad to hear that his injuries are not life-threatening and hope that he makes a full recovery."
The Ulster Unionist Party issued a joint statement on behalf of its Policing Board members and urged anyone with information to contact the police.
It said: "We strongly condemn this brutal and unjustifiable attack on our colleague on the Policing Board who was merely enjoying a quiet drink with his son in a bar when the attack happened.
"The police have confirmed the main suspects so far are dissident republicans.
"However, this is not the first time that they have targeted members of the Policing Board."
Alliance Party deputy leader Eileen Bell said: "This was not just a cowardly attack upon Denis Bradley as an individual, it is an attack upon the rights to build free speech and efforts to make a new beginning in policing."
Meanwhile, a 26-year-old man has been charged with disorderly behaviour after police investigating the attack on Mr Bradley said they were attacked.
Several petrol bombs and other missiles were thrown.