OSHAWA, Ont. - General Motors Canada and Unifor are squaring off before the Ontario Labour Relations Board about whether union workers have engaged in illegal strikes as part of a campaign to stop the closure of GM's assembly plant in Oshawa, Ont.

GM says it filed an application with the board seeking to “stop any further illegal activities” after several labour actions by union members.

Unifor says in its filed response that it denies any violations of the law and that incidents were discrete and quickly resolved.

GM's allegations focus on several incidents where union members halted work or engaged in demonstrations, including on Nov. 26 when the company announced the closure and Jan. 9 when it confirmed it would not reconsider its decision.

Unifor says in a statement that it stands behind the fight to save jobs that depend on the plant, and expects GM to stand up to commitments in the collective bargaining agreement that the company won't close the plant until Sept. 2020.

GM declined to comment beyond confirmation of its filing.