The estimate was given by the commission president, Jean-Marc Sauvé, in an interview published Sunday in the newspaper Journal du Dimanche. The commission has been investigating for 2 1/2 years. Its full findings are scheduled to be released on Tuesday.
In the interview, Sauvé did not give a figure on the number of sex abuse victims but said the report does include a new estimate.
Asked about the commission's work investigating child abusers, he said: "We evaluated their number at 3,000, out of 115,000 priests and church people since the 1950s. Two-thirds are diocesan priests."
He said 22 cases have been forwarded to prosecutors for alleged crimes that can still be pursued. More than 40 cases of alleged crimes that are too old to be prosecuted but that involve suspects who are still alive have been forwarded to church officials, Sauvé said.
"From 1950 to 1970, the church is completely indifferent to the victims: They don't exist, the suffering inflicted on children is ignored," the newspaper quoted him as saying. "The periods that followed were different."
He added: "Our objective is to furnish a concrete diagnosis of all the abuses, to identify the causes and draw all of the consequences."