OTTAWA -- Talks between Canadian National Railway (TSX:CNR) and the union representing nearly 5,000 employees are expected to continue right up until Monday's deadline with the threat of a lockout looming.

The Montreal-based railway said it plans to lockout workers represented by Unifor unless the union agrees to binding arbitration to settle contract differences.

Binding arbitration is something Unifor's president continued to reject on Monday, adding he hoped a settlement could be hammered out.

"There is zero softening" of the union's position on the issue of arbitration, said union president Jerry Dias.

Unifor represents some 4,800 mechanical, intermodal and clerical workers at the railway.

Dias said both sides are pushing towards a settlement in order to avoid arbitration and he expected talks to continue in Ottawa right up until the 11 p.m. ET deadline.

"We still have a long way to go, but the key thing is that both sides are at the table and we're working on it," Dias said.

CN would not comment Monday.

The company maintained binding arbitration "may ultimately be the best way to avoid a lockout of the union's 4,800 members," in a statement published Sunday.

The union, which had announced plans to begin a strike vote next week after the failure of five months of negotiations, rejected CN's arbitration ultimatum last Friday.

The union said there was "meaningful dialogue" between both sides on Sunday.

Last week, the threat of federal legislation prompted CP Rail and the Teamsters to end a one day strike by 3,300 locomotive engineers and other train workers.

Federal Labour Minister Kellie Leitch said Monday through a spokesman she "encourages both sides to continue their discussions," but offered no hint of federal legislation in the current case.

She said federal mediation advisers are present in Ottawa at the talks.

Also Monday, Montreal's commuter train operator, AMT, said it received assurances from both CN and Unifor that unionized employees who maintain and inspect the city's Deux-Montagnes train line would keep it operational.