Canaport LNG LP was charged with three violations in October 2014 and two other companies — Irving Canaport GP Company Ltd. and Repsol Canada Ltd. — now also face those charges.
The three companies face two charges under the federal Migratory Birds Convention Act that prevent anyone from depositing a substance harmful to migratory birds.
They are also charged with unlawfully killing Canada warblers under the federal Species at Risk Act.
Environment Canada launched an investigation after about 7,500 migrating birds were killed in September 2013 while excess gas was being burned-off at the facility.
The case is scheduled to return to provincial court in Saint John on May 7 for the companies to enter pleas.