An employee of the mayor's office has resigned after it became publicly known that he called an Ottawa radio phone-in show under a fake name to support a proposed snow tax.

Mayor Larry O'Brien told CBC News on Wednesday afternoon that Dave Gibbons, special assistant to the mayor, had left his post.

Hours earlier, Gibbons posed as someone named "Tom" and called into The Chat Room, a show hosted by Mark Sutcliffe on radio station CFRA.

He defended the idea of a $50-per-household tax surcharge to help pay the city's huge snow-removal bill this year. The mayor had publicly proposed the idea on Tuesday afternoon.

Since then, online message boards and radio phone-in shows have been flooded with comments from Ottawa residents, most opposed to the levy.

The mayor was asked about "Tom" after some listeners heard him on the radio and noticed he sounded like Gibbons.

O'Brien confirmed to reporters that Gibbons had made the call while talking to them about the snow tax just before noon.

"I think it is absolutely unacceptable ... I am angry about that," he said. "He confirmed in fact that he had made a mistake, so I'm going to go back and talk to him about that immediately following this meeting."

Heavy snow means bulkier budget

Still, the mayor stood by his idea on Wednesday. He reiterated that at the current rate of snowfall, the city would exceed its $65-million snow-clearing budget by $23 million.

"One way or another, it has to be dealt with," he said.

The city is trying to rebuild its dwindling reserve fund, but this year the fund doesn't contain enough money to cover the city's projected snow-clearing shortfall, O'Brien added.

However, he noted that his is only one vote on council.

Other councillors have expressed little support for the levy.

Ottawa has received more than 400 centimetres of snow this winter.

The $50 tax surcharge would represent a tax increase of around two per cent for a household that pays a typical property tax bill of $2,500 a year.

It would be on top of a property tax increase of 4.9 per cent next year and in spite of O'Brien's election promise to freeze taxes for four years.