Canada's major banks are heading into a renewed mortgage price war in the wake of the Bank of Canada's surprise decision to cut interest rates.

Mortgage brokers reported that Royal Bank of Canada dropped its five-year fixed rate for qualified borrowers to 2.84 per cent over the weekend. While smaller, non-bank lenders have started offering even cheaper rates, RBC's rate cut is likely a record for a major bank, said Drew Donaldson, executive vice-president of Safebridge Financial Group. The bank also slashed its posted 10-year fixed rate to 3.84 per cent, the lowest nationally advertised rate in the country, said Robert McLister, founder of Ratespy.com.

RBC spokesman Wojtek Dabrowski said the bank continues to "review the impact of the Bank of Canada's rate decision," and that the company's "individual product lines continue to make pricing adjustments in the regular course of business to ensure we provide competitive rates in the marketplace."

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Bank of Nova Scotia and National Bank of Canada have also cut fixed rates on broker-originated mortgages by 10 to 20 basis points in recent days. Toronto-Dominion Bank said it was dropping its posted 5-year fixed rate on Tuesday to 3.09 per cent, down from 3.29 per cent.

Mortgage officials said RBC was among the last of the major banks to introduce new rate specials.

"National Bank already offers competitive rates over the mortgage rate spectrum as we moved early over the past weeks," bank spokesman Claude Breton said.

A battle in the mortgage market seemed inevitable given that Government of Canada bond yields have plummeted in recent weeks, falling 57 basis points in the past month to historic lows. Brokers had predicted that falling bond yields were almost certain to drive down the fixed-rate mortgage pricing ahead of the competitive spring housing market even as banks have largely kept their prime rates, which govern variable-rate mortgages along with other types of loans, unchanged. All the major banks will soon be forced to follow the Bank of Canada and cut their prime rates 25 basis points to 2.75 per cent, Mr. Donaldson said. "We expect more cuts to come from all lenders," he said.

Even ahead of the Bank of Canada's unexpected rate cut last week, the country's major banks already seemed poised for a new round of rate cuts this year. Earlier this month, Bank of Montreal chief executive officer Bill Downe told an industry conference the bank was expecting to "again have a fresh offer that is appealing to customers" in the spring. The bank drew the ire of former finance minister Jim Flaherty in 2013 after it dropped its five-year fixed mortgage rate to 2.99 per cent in what Mr. Flaherty called a "race to the bottom."

The renewed price war is raising concerns that the central bank's rate cut will add fuel to the country's overheated housing market even as Canadians struggle under the burden of rising household debt. Canadian Imperial Bank of Commerce deputy chief economist Benjamin Tal warned last week that falling mortgage rates could lead to "a monstrous spring in the real estate market."

Others argue that low rates may not be enough to kick start a housing market that had already begun to slow toward the end of this year as oil prices plunged. Even as they predicted that Canada's central bank will cut interest rates a second time later this year, TD economists said Monday they expect Canada's real estate market to fare poorly this year as cheap crude and sky-high house prices in major cities are making it difficult for new buyers to afford to jump into the market despite low mortgage rates. "The housing market is … projected to be a drag on growth, with changes in existing home sales and prices, as well as housing starts, forecast to tilt into negative territory," the bank said.