CHIEF Constable Simon Byrne has vowed "vigorous action" to catch those behind threats against journalists and other public figures.
He was speaking after sinister graffiti appeared targeting the Irish News security correspondent Allison Morris and Sunday World journalist Patricia Devlin.
Sinn Féin MLA Martina Anderson and footballer James McClean have also been subject to online threats in recent days.
"Threats to journalists, political leaders and other high profile individuals must stop immediately," the chief constable tweeted.
"In addition to keeping the victims of the threats safe, the PSNI will vigorously pursue those involved.
"There is no place in society for these unacceptable actions,"
Deputy First Minister Michelle O'Neill branded the threats and online abuse directed at her party colleague and Derry-born McClean as unacceptable.
She said there can be no place for the malicious harassment online or daubed on walls.
"There has been a concerning increase in malicious online harassment, threats and abuse recently directed at public figures – all of these threats and abuse are absolutely unacceptable," the Sinn Féin vice-president said.
"A free press is central to a democratic society and journalists must be protected from the threat of violence and harassment in carrying out their important work.
"Equally, it is a democratic imperative that public representatives are able to represent their constituents free from abuse and threats of violence."
The Mid Ulster MLA plans to raise the matter in the assembly today.
"Where members of the public have information in regards to such abuse it should be reported to police, and where relevant social media platforms so action can be taken to protect individuals from this harassment and malice," she said.
First Minister Arlene Foster also condemned the threats against journalists.
"Attempts to bully and intimidate Allison and other journalists are disgraceful," she tweeted.
"Such threats have no place in a democracy."
Foyle Assembly member Ms Anderson said she had reported "vile and despicable" abuse received on social media in recent days to the police.
Republic of Ireland international James McClean and his wife Erin have spoken out in the last couple of days about the abuse their family have received over the past nine years, which have included death threats.
