Incumbent Mayor Sam Katz is accusing his chief opponent in Winnipeg's upcoming civic election is using unionized workers from outside Manitoba to work on her campaign.

Katz said he didn't have specifics about just how Judy Wasylycia-Leis was going about importing and using the workers, but said he's heard rumblings that it's happening.

"We don't have any private detectives working for us, I can tell you that," he told CBC News.

'This is a civic election where people living in the city of Winnipeg are the ones who are going to be impacted. Do you want people coming from other countries as well?'—Sam Katz

"But people are coming in from [other] provinces. I have very little doubt they are union workers. I can tell you that if that's what you're asking me. No doubt whatsoever," Katz said.

"This is a civic election where people living in the city of Winnipeg are the ones who are going to be impacted. Do you want people coming from other countries as well? Maybe," Katz said.

Katz's comments come just a day after he told a mayoralty forum that a person claiming to be from the Canadian Union of Public Employees phoned an elderly widow of a city worker and said a vote for Katz meant her pension benefits would be affected.

Wasylycia-Leis has denied any knowledge of that incident and said it would be against municipal election rules to bring in out-of-province unionized workers.

The former NDP MP repeated that she is not endorsed by any union, nor has she sought an endorsement from one.

Wasylycia-Leis, however, said the Winnipeg Police Association and the United Firefighters of Winnipeg have publicly endorsed Katz.

The groups are the respective unions for the rank-and-file members of the police service and city firefighters.

According to recent polls, Katz is in a neck-and-neck race with Wasylycia-Leis as he seeks a third term in office.