Projet Montréal councillor Laurence Lavigne says she received documents from the STM with the new fare schedules.
She has tweeted a photo of those documents.
According to the documents, the cost of a single fare will go up from $3.00 to $3.25.
The cost of a monthly pass will go up $79.50 to $82.
STM spokeswoman Isabelle Tremblay would not confirm the fare hike.
"We have nothing to say until our press conference tomorrow," she said.