Police investigating the murder of policeman Stephen Carroll in Craigavon a week ago arrested two more suspects today.
The men, aged 31 and 27, were detained in Craigavon, Co Armagh, this morning, police said.
Police and community representatives are working to try and extinguish heightened tensions in Craigavon after a weekend of civil unrest.
Last night two cars were hijacked and set alight close to the entrance of the Drumbeg estate.
Railway services in the area were also disrupted following reports of a suspicious object left on the line.
Rioters also took to the streets of Lurgan over the weekend as officers arrested republican Colin Duffy and Declan McGlinchey — the son of murdered INLA man Dominic McGlinchey — in connection with the murders of two soldiers at Massereene barracks in Antrim.
Officers were pelted with missiles and rioters removed railway crossing barriers which they used to block the road during disturbances on Saturday.
Eleven people are now being questioned in connection with the dissident republican murders of the two soldiers and a policeman.
Constable Carroll (48) was shot while on duty in Craigavon last Monday by the Continuity IRA. Soldiers Mark Quinsey (23), from Birmingham, and Patrick Azimkar (21), from London, were shot dead at Massereene barracks in Antrim by the Real IRA.
Upper Bann MLA Stephen Moutray said the “small group of people responsible for this pointless criminal activity are destroying their own communities and act on behalf of |no-one”.
“The police have the overwhelming support of the community in ensuring those young people responsible for this thuggery are apprehended, brought before the courts and severely dealt with,” the DUP man added.
Meanwhile, the Belfast Telegraph has learned that plans for a parade in Belfast for soldiers returning from Iraq were abandoned after the murders.
Following the recent upsurge in dissident republican violence the homecoming parade planned for the Queen’s Royal Hussars detachment later this year has been shelved.
A heightened security presence has been visible on the streets over the past week with a large number of vehicle checkpoints being carried out by armed officers.
With the threat of further attacks on the security forces still high, officers and new recruits have been briefed on additional security measures they should take while on and off duty.
Police have said the number of republican dissidents trying to wreck the Northern Ireland peace process is about 300.
Chief Constable Sir Hugh Orde said yesterday that intelligence showed the numbers intent on violence was a tiny proportion of the population.
Sir Hugh said: “Of course, the threat is very dangerous, that's been evidenced in the last week, but it's a very small group. Three hundred people in a population of 1.7m people puts it in perspective but it's a threat we take seriously.”
He also rejected as “ridiculous” media stories that attacks on politicians elsewhere in the UK were being hatched.