Two candidates vying for a council seat in Ward 4 are locked in a heated debate about exactly how much of London's property taxes will go toward the city's Bus Rapid Transit system.

It began when candidate and former councillor Stephen Orser handed out flyers that warn voters about a "BRT tax" he said may result in a property tax increase of $1,000 to $1,200 a year for the average home.

The flyer says Coun. Jesse Helmer — who is running for re-election in the ward — "strongly supports this BRT tax." The flyer also lists phone numbers for Helmer's campaign office and his cellphone.

Helmer calls Orser's number "total nonsense." Most of the cost of BRT will be covered by development charges.

The property tax portion of BRT costs will amount to less than $10 a year per household, Helmer says.

Orser was not available for an interview with CBC News on Wednesday.

But his campaign manager Fiona Graham said Orser stands behind the numbers in the flyer.

In a YouTube video, Jesse Helmer says the claims of a BRT "tax" being made in a flyer handed out by opponent Stephen Orser are 'totally false.' (YouTube)

City officials: 'We're confident in our cost estimates'

BRT project director Jennie Ramsay says the numbers in Orser's flyer are not an accurate reflection of how BRT will affect property taxes.

Here's how she lays out the costs.

In terms of capital (not operating) costs, BRT is slated to cost $500 million.

The city's portion of that is capped at $130 million, with senior governments picking up the balance. Ramsay said the bulk of the city's share will be covered by development charges, money developers pay to cover added infrastructure costs.

In a fact sheet sent to CBC, Ramsay's office says this about the property tax impact:

"The current budget already accounts for the property tax portion of London's $130-million share of the capital costs of BRT. Capital costs are one-time and do not permanently increase taxes."

So exactly how much will come from property tax? She expects that figure is about $12-million spread over the 10 years of the project. The $12-million figure is based on a 2014 study of development charges revenue.

"We're confident in our cost estimates for the project and what's reflected in the development charges background study," said Ramsay. "The actual property tax impact to Londoners is quite minimal."

She also said her office has factored in a contingency fund for any cost overruns.

Helmer: BRT a 'great deal' for property tax payers

Helmer posted a YouTube video and Tweets calling Orser's claim of a BRT Tax "total nonsense."

"It's not true, it's not even close to being true," he says. "As my grandma would say, it's poppycock."

Helmer says the property tax portion of the BRT amounts to less than $10 a year for the average household, and 2.5 per cent of the overall project budget.

"We have a candidate who's more interested in getting elected than in telling the truth," said Helmer.

Orser campaign manager: we need more cost information

Stephen Orser's campaign manager Fiona Graham said there are still questions about how much BRT will wind up costing taxpayers.

"People are entitled to information and I don't think people were even aware that there is a BRT tax that is going to be applied to our house taxes," she said.

Graham said there are plans to distribute up to 25,000 more of the flyers in Ward 4.