The High Court has heard that drones may have been used to deliver unlit petrol bombs to locations close to the former Crown Paints factory in Coolock in Dublin.
Lawyers for the developer and leaseholder of the site told the court it seemed the incendiary devices were being dropped near the property where they could be collected by unknown individuals.
Last week, the court granted an injunction preventing "persons unknown" from engaging in threatening or intimidating behaviour at the factory or interfering with employees or contractors as they carry out their work.
The building had been designated to house international protection applicants and has been the scene of protests and violence in recent days.
Senior Counsel, Bernard Dunleavy representing the developer Remcoll and leaseholder Townbe, told Mr Justice Rory Mulcahy the order he made last week wasn't working and that there had been five fires at the scene in the six days since it was made.
The judge was told the developer and leaseholder have been unable to attach written copies of the injunction to the factory gate because of safety concerns.
The court also heard the Chief Executive Officer of Remcoll has left Ireland on the advice of gardaí.
Mr Dunleavy said there was a "crackle of violence" at the scene that gardaí feared would spark into flames.
The judge extended his orders today and allowed the injunctions to be served on "persons unknown" and four individual defendants by publishing the details in two national newspapers and in one case on the social media site X.
Three of the individuals added as defendants are: Sean Rush, of Edenmore Avenue, Coolock; Kevin Coyle, of Corbally Rise, Saggart; and Leon Bradley, of Virginia Park, Finglas.
A fourth man was joined as a defendant but can not yet be named as his address has not been identified by the companies. The court heard more defendants will be added to the case as they are identified.
The judge again refused the companies’ request for the injunction to apply to a 100m "exclusion zone" around the former factory.
More than 20 people have been before Dublin District Court charged with public order offences relating to recent incidents at the site.
They have been granted bail on condition they stay away from the factory.
The court heard last week that the site is due to be developed to accommodate mainly Ukrainian people who have fled the war.
It is planned to house up to 500 international protection applicants there.
The case is back in court next week.
