Mayoral candidate George Smitherman says he didn't swear at a campaign volunteer for rival Rocco Rossi. (Canadian Press)

Toronto mayoral candidate Rocco Rossi demanded Friday that rival George Smitherman apologize for allegedly swearing at a campaign volunteer before a debate.

Rossi said a young woman working for his campaign offered Smitherman a campaign flyer ahead of a debate on youth issues at the University of Toronto on Thursday night. Smitherman "swore and was verbally abusive to her," Rossi said.

"I took her piece of paper and let her know what I thought of it," Smitherman said later Friday, adding that the woman had stepped in front of him as he was entering the debate.

When asked if he swore at the woman, Smitherman replied: "No, absolutely not."

The Rossi campaign would not release the name of the volunteer, saying she wants to maintain her privacy.

"This has been extremely upsetting to her," Rossi said.

"We've demanded an apology. It's not behaviour befitting a public official and someone wanting to be mayor of the city."

Erika Mozes, a spokeswoman for the Smitherman campaign, said he was the only candidate who came to the debate with a plan on how to boost youth employment.

"Obviously, there were some feelings that might have been hurt," Mozes said. "As George said last night as well, there's been a lot of things that have been said about him, and you know, this is politics."