Residents near the Poolbeg Incinerator are calling for clarity over the source of an "infestation" of flies in the area.
The incinerator has been identified as a possible source, after people in surrounding areas complained of a massive number of the winged pests.
The operator of the facility, Covanta, says it's not the source of the problem.
But the Environmental Protection Agency (EPA) says an inspection last Friday found "moderate fly numbers" in the waste intake building and bunker area.
A pest control contractor was called to the site on July 2nd, 5th and 6th to deal with fly control.
The EPA says it has instructed the company that runs the incinerator to continue fly treatment, as necessary, to ensure that fly populations do not increase on site.
The EPA will continue to monitor the situation.
Fianna Fáil's Dublin spokesperson John Lahart says: "Residents in Ringsend, Sandymount and Irishtown are justifiably angered by the current fly infestation which has hit the area.
"Locals say there have been an unprecedented number of flies in the villages in recent days with people forced to keep their windows shut.
"Despite an initial statement from Covanta claiming that the incinerator was not to blame, the EPA claimed that it recorded low to moderate infestation at the plant during a recent inspection.
"These conflicting reports don’t add up and residents deserve a concrete answer as to what is causing the usual increase in the fly population in the area. "
He says the Department of Environment should carry out an investigation to determine the root of the problem.