OTTAWA -- Postmedia Network Inc. (PNCa.TO) has told Ottawa Citizen and Ottawa Sun staff that it will lock out union employees starting Monday if they reject or refuse to vote on its final contract offer Sunday.

Chris Krygiel, vice president of human resources and labour relations at Postmedia, said in a letter Thursday to staff that a lockout is not the company's preferred course of action, but that both sides have to "move on" from a collective agreement that expired 34 months ago.

He said the company has made the best offer it can on benefits given the economic challenges of the industry. Postmedia has struggled under significant debt and declining advertising revenue in recent years.

Lois Kirkup, vice-president of the Ottawa Newspaper Guild, said the company is asking for significant cuts on top of agreed-upon concessions that included a shift to a defined contribution pension.

"They're actually gutting our benefits," said Kirkup.

The local Communications Workers of America union representing 63 staff at the papers has set a meeting for Sunday to discuss a possible vote on the company's offer, though Kirkup said the union will ask for an extension of the company's deadline to Wednesday so that more members have the opportunity to participate.

Montreal Newspaper Guild president Ron Carroll said members would walk out in solidarity with the Ottawa union in the event of a strike, as part of a wider agreement among Postmedia unions to push for similar contract terms.

"Members of the Ottawa and Montreal Newspaper Guilds will not fold in the face of unacceptable concessions or by a threat of a lockout if we do not roll over to their demands," Carroll said by email.

Krygiel said in the letter that if a labour disruption does happen in Ottawa, the company will examine all of its options including job cuts, which could be permanent.

"Before you decide to reject this offer, triggering a labour dispute, please take into consideration the implications of taking such a dramatic step," he wrote.