The managing director of Kent-based advisory firm Mortgages for Business, said the increasing cost of funding mortgages would eventually be passed on to customers, despite a currently buoyant market.
He said three-year rates were virtually the same as when swap rates bottomed out in April 2013, while five-year costs were around 0.1 per cent a year higher.
However, with swap rates having risen by up to 1 per cent in the corresponding time period, Mr Whittaker expected providers to hike up the cost of lending.
He said: “Competition is set to intensify further still, but ultimately, lenders will have to recognise the increasing cost of funds.
“While lender margins are likely to fall, it’s highly likely interest rates will rise on medium-term fixed-rate mortgages, reflecting the impending rise of the bank rate.
“That’s why we maintain our advice to investors to consider five-year fixed-rate mortgages.”
His comments came as speculation mounted over the Bank of England’s decision on monetary policy. At Davos in January, Mark Carney, governor of the BoE, said there was “no immediate need” for rate rises, despite his condition for doing so being met, as unemployment contracted to 7.1 per cent.