TORONTO (Reuters) - Royal Bank of Canada (>> Royal Bank of Canada) had seen increased demand for mortgages ahead of tougher tests for borrowers being introduced in January, a top executive said after the bank reported better-than-expected quarterly earnings.

Canada's banking regulator last month finalised tougher new rules on mortgage lending aimed at safeguarding lenders and borrowers. The B-20 rules, which take effect in January, mean borrowers taking out uninsured mortgages must be stress-tested to determine their ability to make repayments at a rate 200 basis points above their contracted mortgage.

Their pending introduction has led some borrowers to rush to get a mortgage before the stricter tests take effect, Neil McLaughlin, RBC's head of personal and commercial banking, told analysts on a conference call.

"We have seen a little bit of pull-forward this fall," he said. "As we talk to customers some of them are surprisingly aware of exactly what the stress test is about and have decided to move more quickly."

McLaughlin said RBC had reviewed how the new rules will affect its mortgage book in the longer term and expected the impact to be "fairly modest."

Bank of Nova Scotia (>> Bank of Nova Scotia) said on Tuesday that about 5 percent of new mortgages would be affected by the rules and McLaughlin said RBC would expect to see a similar number.

"Over 90 percent of our mortgages are already underwritten at these higher rates so the vast majority of our originations are not going to be impacted," he said.

RBC, Canada's biggest bank by market value, on Wednesday reported fourth-quarter earnings that beat analysts' forecasts. The bank has beaten market expectations in each quarter of the past year, brushing off concerns about Canada's housing markets and record levels of household debt.

Earnings per share excluding one-off items rose to C$1.92 in the quarter to Oct. 31 from C$1.65 a year ago. Analysts had on average forecast earnings of C$1.87, Thomson Reuters I/B/E/S data showed.

On Tuesday, Scotiabank (>> Bank of Nova Scotia) reported earnings that were below market expectations.

Toronto-Dominion Bank (>> Toronto-Dominion Bank) and Canadian Imperial Bank of Commerce (>> Canadian Imperial Bank of Commerce) will report earnings on Thursday.

"These RBC results provide a more positive read through to peers and should help stabilize sentiment around the bank group," said Eight Capital analyst Steve Theriault.

Shares in RBC were up 0.6 percent at 1030 EST. They have risen by 10.5 percent since the start of the year, making it North America's fifth biggest bank by market value.

(Reporting by Matt Scuffham; Editing by Chizu Nomiyama and Bill Trott)

By Matt Scuffham