A month-old strike at Canada Post will drag on after support workers rejected a company contract offer.

The Public Service Alliance of Canada says more than two thirds of about 2,100 union members voted against the offer in a weekend vote.

Canada Post announced Friday that a tentative contract had been reached, but the union called on workers to reject it.

Union president John Gordon said the two sides reached agreement on most issues, with the exception being a new short-term disability system put forward by the employer.

He said the offer would have replaced sick leave and family-related leave with a new system allowing a private insurer to determine whether a worker gets sick leave.

The offer included a 2.5 per cent salary increase over the first two years and a 2.75 per cent increase over the third and fourth years of the contract