Brad Cabana has filed a counterclaim with the province's Supreme Court alleging that Williams' statement of claim contains accusations not based on fact.
In the document, Cabana also alleges Williams made comments on a popular call-in radio talk show that aired July 10 that suggest the political blogger "is of the character to destroy reputations to simply achieve a disruptive end."
"The plaintiff further believes the defendant understands his popularity with the people of Newfoundland and Labrador and deliberately used that popularity to publicly denigrate opponents to his vision of the Muskrat Falls project," Cabana argues in the counterclaim.
The counterclaim also names Alderon Iron Ore Corp. (TSE:ADV), a mining company that has also launched a defamation suit against Cabana. It alleges that Alderon's lawsuit, like Williams's, is intended to "nullify his criticism of the Muskrat Falls development."
The lawsuits against Cabana allege he suggested that the deal to develop the multibillion-dollar Muskrat Falls project is engineered to make money for Williams and mining interests at the expense of customers who will be saddled with debt and higher utility bills.
Those statements of claim — which also name Sierra Club Canada and its spokesman Bruno Marcocchio — say the defendants wrongfully suggested Williams, who sits on the board of Alderon, would benefit from a proposed royalty trust deal to finance the project.
Sierra Club Canada has not filed a statement of defence. All allegations contained in the statements of claim and counterclaim have not been tested in court.
The executive director of Sierra Club Canada said last month that the group hopes to resolve the matter "amicably."
Williams was premier when the provincial Tory government announced a term sheet in 2010 to develop the Muskrat Falls development, which is expected to cost more than $6.2 billion if it proceeds.
The government is to decide later this year whether to sanction the project after a debate in the legislature and updated cost projections.
Also on HuffPost