SASKATOON -- The union that represents letter carriers in Saskatoon says its members have been ordered by Canada Post to deliver a graphic anti-abortion flyer that targets Liberal Leader Justin Trudeau.

Julee Sanderson, president of Canadian Union of Postal Workers Local 824, said some letter carriers are upset about the flyer and have balked at delivering them.

"There are carriers who are certainly concerned about the violent, graphic material that they are delivering and they are concerned about who in the home is going to be receiving that," she said Wednesday.

"CUPW supports our members who feel they have a legitimate concern that a corporation like Canada Post should work to preserve family values."

Sanderson said the flyer from a group called the Canadian Centre for Bio-Ethical Reform is in a white envelope that says "Important Election Information Enclosed."

The flyer itself includes a picture of an aborted fetus and of Trudeau.

It includes a statement that says Trudeau supports abortion until birth and "a vote for Justin Trudeau is a vote for this," referring to the picture.

Sanderson said Canada Post has told the union that the corporation is not responsible for the content of mail and is legally obligated to deliver the flyers.

The envelopes are to be delivered throughout much of the city later this week.

"We are responsible for the physical delivery of all mail in Canada. We do not have the legal right to refuse delivery of a mail item because we or other people object to its content," Matt Ziebarth, a Canada Post manager, told the union in an email.

"Anyone who has concerns about the content should either contact the publisher or simply dispose of it."

Canada Post responed to a request for comment with a similar statement. The company did not answer questions about whether it has a policy on what it will or will not deliver as flyers.

Sanderson said letter carriers who refuse to deliver the flyer could face disciplinary action from Canada Post.

The Conservatives have dominated Saskatchewan in recent federal elections. The party won 13 of 14 seats in 2011. But with redrawn electoral boundaries, observers have suggested a handful of those seats could be in play in the upcoming vote.