More police officers were injured as heavy masonry and fireworks were thrown during disorder on Friday night, the Police Service of Northern Ireland (PSNI) has said.
A senior officer warned that the force is actively investigating people inciting the disorder through social media.
The scenes on Friday night in Portadown were the fifth consecutive night of rioting in the region after serious disturbances in Ballymena on Monday.
The violence, which followed an alleged sex attack on a teenage girl in the Co Antrim town, has since spread to several other parts of Northern Ireland.
On Saturday afternoon, hundreds of people attended a rally in Belfast city centre which heard calls for greater political leadership in opposing racism.
More than 60 police officers have been hurt during the rioting.
A PSNI spokesperson said: âDisorder and violence broke out in Portadown with officers coming under sustained attack with heavy masonry and fireworks thrown at them.
âOfficers used various public order tactics including water cannon to keep the public safe with no reports of injury to the public or damage to property.â
Two males, aged 14 and 20, were arrested on suspicion of riotous behaviour and remain in custody.
Police in Londonderry dealt with disorder in the Tullyally area.
A police vehicle was damaged, with the front window smashed.
One male was arrested at around 2.20am and remains in custody.
Damage was caused to playing fields and property in the Killeavey Road area of Newry as a large group set a pitch and bins on fire. One 14-year-old male was arrested on suspicion of riot.
Stones were thrown at the windows of a hotel in the Newtownabbey area and a car was set on fire in the Hesketh Gardens area of Belfast, which police are treating as a racially motivated crime.
The disorder started in Ballymena on Monday after an alleged sexual assault of a girl in the town last weekend. Two 14-year-old boys, who spoke to a court through a Romanian interpreter, have been charged with attempted rape.
A peaceful protest about the alleged assault on Monday evening was followed by attacks on properties housing ethnic minorities and police. The PSNI described the scenes as âracist thuggeryâ.
Assistant Chief Constable Melanie Jones said: âItâs deeply disturbing to see such young members of our communities involved in and in some areas driving criminal activity like this.
âI would appeal directly to parents and guardians to speak to your children about the impact their behaviour is having on the safety of our local communities and the impact this could have on their lives if arrested, charged and prosecuted.
âWe continue to have a heightened presence in our local communities to de-escalate violence and we are making arrests and will continue to make public appeals with photos of suspects.
âDo you want your child, family member or friend directly associated with this disorder in this way? These actions are not without serious consequence.
âI am so grateful to our frontline officers who continue to put themselves at risk in protecting everyone from this hate-motivated criminality.â
Ms Jones added: âTo those posting hate on social media, inciting disorder or being seen to commit disorder, we are actively investigating what you have said and what you have been captured doing.
âWe have an ongoing physical and online presence.
âAs our investigation continues, we have already released images of four individuals we want to identify and interview in connection with our ongoing investigation.
âIn releasing these images, I am asking the wider community to step forward and help us.
âIt is in all of our interests, and in the interests of justice, that those responsible are dealt with and I would urge anyone who may have information to bring it forward.
âIt is important to know over the remainder of this weekend the public will continue to see a large policing presence across Northern Ireland to reassure our communities and protect our streets.
âThis will include the deployment of mutual aid resources from Scotland. These officers, trained to work in our environment, will be working side by side with their PSNI colleagues.
âWe repeat, once more, our appeal for calm across Northern Ireland in the coming days.â
