Jeff Burch is asking Ontario's Integrity Commissioner to conduct an investigation into a zoning order in Stratford.
It requires the city to accept a float glass factory and the NDP MPP for Niagara Centre expressed believes the order from the Ford Government violates the Lobbyists Registration Act.
His letter claims that Xinyi secretly negotiated with the Ford government for about two years.
Burch says that local people should make the decision on if they want the glass factory there, not Doug Ford.
"It's unacceptable for Ford to override public consultations with the local community, unions and environmental advocates and it looks like he’s doing that because he negotiated a backroom deal with this multinational corporation, Xinyi."
NDP Environment critic Ian Arthur is also against the proposed plant, saying that it threatens farmland.