Surveillance on dissident Republicans and Republican groups will be stepped up by gardai ahead of a massive protest against water charges on December 10.
Sources say that garda officers will be carrying out “overt and covert surveillance” on known dissidents ahead of the protest and on the day itself. Social media will also be monitored.
It comes as protesters looking to cause trouble at next month’s demonstration have been told to stay away by organisers.
“Certain groups and certain people will be monitored and this will happen before the day itself,” a senior source pointed out.
The surveillance revelation comes as officers based in Store Street Garda Station launched an investigation after a letter from a previously unknown dissident grouping called ‘Irish Republican Action’ was sent to the offices of the Herald yesterday.
The letter stated that on December 10 protesters “must make the Love Ulster rally look like a tea party”.
Gardai are working on establishing the credibility of the letter.
However, gardai stress that they expect the vast majority of those attending the protest next month to act in a completely lawful manner and the reason for surveillance is concerns that violent dissident groups may try to “hijack” the event which is expected to attract tens of thousands of people.
Socialist TD Paul Murphy, who is helping to organise the demonstration, said trouble makers were not welcome.
“We don’t want anybody turning up to cause trouble. I’d say if anyone wants to cause trouble, don’t turn up,” he said.
Mr Murphy said the protest would be well attended by stewards and he was unaware of any plan to disrupt the demonstration with violence.
“I think if we could get 50,000 people, that would be a massive success,” he said.
Meanwhile, investigating officers have formally interviewed a second government minister over the violent and unruly anti-water charges protest.
Minister for State at the Department of Social Protection, Kevin Humphreys, spoke to investigating officers for an hour at Leinster House yesterday.
Mr Humphreys was present at a graduation event in Jobstown last Saturday week. The Dublin South East TD gave a detailed account to gardai about the protest, which has been strongly condemned after quickly descending into violence.
Officers are continuing their investigation into the violent scenes .
It is understood that a number of suspects have been identified for a range of crimes including public order offences as well as thefts and attempted thefts of garda equipment.
In a separate incident, gardai are investigating after suspected human excrement was smeared all over an Irish Water registration form.
Two staff at a Cork-based processing sub-contractor had to be given precautionary medical tests after the letter was opened and handled.
Another staff member, who spotted the letter after their colleague had shouted in horror, immediately felt ill and complained of faintness.
Gardai are treating the matter seriously. The letter was seized and is now undergoing forensic tests to try to determine its precise origin.