The UDA and UVF have united to condemn a loyalist threat to use violence against children at three Catholic schools.
And the DUP's most senior councillor in Belfast last night accused those behind the threat from the 'Red Hand Defenders' of attempting to raise tensions through "false rumours".
Police are expected to maintain a low-key presence at Mercy Primary School, Mercy College and Holy Cross Primary in north Belfast after a man claiming to be from the Red Hand Defenders said parents, pupils and teachers were not welcome at schools in "Protestant, unionist and loyalist areas".
He added that "military action" would begin today if the threat was not taken seriously.
Making the warning in a call to two Belfast newsrooms on Friday, the man said the threat had been "reactivated" due to "attacks on the Protestant, unionist and loyalist community in recent months".
Police have indicated there is no evidence to corroborate the threat but that it cannot be ignored.
The North Belfast Ulster Political Research Group – which provides advice to the UDA – said: "We condemn any threat completely and without equiviocation, from whatever source. It is particularly vile, without justification or cause, to issue threats against schools, workers or protesters."
Oldpark DUP representative Lee Reynolds also condemned those behind the threat.
"There are persistent attempts to increase tensions in north Belfast, often through false rumours and claims. The threats against the schools story is the latest example," he said.
"I urge everyone to treat what they hear or read with care in the knowledge people are playing games."
The PUP – which has links to the UVF – added its condemnation, claiming that the situation was a "cynical republican attempt to heighten tensions at Holy Cross school".
The party accused republicans of using the guise of Red Hand Defenders to try to create a situation at Holy Cross "to diminish the impact of Civil Rights Camp" – a reference to the ongoing loyalist protest against parade restrictions in north Belfast.
Education Minister John O'Dowd said the threats were very disturbing.
"Regardless of anyone's politics or views, schools should and must be havens for the young people who attend them and the staff who work there," he said.
"As Education Minister my priority is to ensure that children are educated in a safe and secure environment, free from threat or intimidation. I believe this is a priority all our society should share."
Veteran republican Sean Murray said retaliatory graffiti had been daubed in west Belfast in response to the alleged loyalist threat but that this did not have the support of the community.
The graffiti, on a gable wall on the corner of the Springfield Road, threatened loyalist workers at the nearby FG Wilson plant. Mr Murray said it had no backing from the community and has now been removed.
"Some of the community representatives have been in touch with quite a few families they are naturally concerned about the safety of kids coming to school, there is a lot of tension," he said.
Mr Murray said he understood there was a lack of evidence surrounding the threat but due to "the legacy" of Holy Cross police had to keep an open mind.
Sinn Fein MLA for North Belfast Gerry Kelly has called on those responsible to withdraw the threat, slamming it as a "disgraceful and sinister statement".
"Those responsible have threatened violent action against children," he said. "People will remember the shameful scenes of school children at Holy Cross where primary pupils and their parents were left traumatised. We can never see a repeat of those scenes."
A PSNI spokesman said police have agreed with school principals the nature of the protective policing that will be delivered in north Belfast this morning.
"As with any operation, this will be proportionate to the environment encountered," he said.
Police also called on community leaders and those in positions of influence to play an active role in diffusing the tension and maintaining calm.
The Red Hand Defenders was formed in 1998 by loyalists opposed to the peace process at the height of the Drumcree crisis, although it is widely believed to be a cover name for hardline elements of the LVF and UDA.
Most notoriously, the RHD claimed responsibility for the murder of lawyer Rosemary Nelson, who had represented a number of republicans in court, in March 1999.
It claimed a number of other murders and also to have left a suspect device at gates at Holy Cross Primary School in January 2003.
Loyalist death threats against the school and violent protests outside it meant children and parents needed a police escort to get to classes in 2001 and 2002.