One illustration of this is the blowout in the gap between the cash rate set by the RBA and the key industry benchmark, the bank bill swap rate (BBSW). The BBSW has shot up by about 25 basis points in the past six months, raising the cost of the banks' wholesale debt, which accounts for about 30 per cent of their funding. Philip Bayley, principal of credit market consultancy ADCM Services, said the previous link between the BBSW and the cash rate was "broken" and this was a sign global funding markets were pushing up the cost of money. "I think what that's telling us it that we are seeing pressure coming through markets to raise rates, rather than the RBA doing it. Part of the reason markets are doing that is because rates are going up all over the world," Mr Bayley said.

If these funding pressures remained for the long-term, he predicted banks would move their rates again. "People are saying now that the RBA is going to stay on hold into 2020. If that's the case, we are definitely going to see more out-of-cycle rate rises [by the banks] over that period," Mr Bayley said. Sean Keane, managing director of Triple T Consulting, agrees that further rate rises from banks were "highly likely" if the RBA left interest rates unchanged and did not seek to address the rise in banks' funding costs. "Whether there's more to come will depend on whether wholesale market rates remain elevated," he said. "The longer they remain elevated, the more likely it is they go up again." "I think it's highly likely [that banks raise rates] if the pressures remain and the RBA chooses to only focus on the cash rate."

However, not everyone agrees. AMP chief economist Shane Oliver says what the RBA does with the cash rate is still the most important factor for consumers with mortgages. Dr Oliver said he thought banks had more than compensated for the increase in their funding costs, and unless there was a further worsening in credit costs, banks would not have a case to hike rates independently of the RBA. Loading "I think it's unlikely," he said. "To get that to happen, you would have to have unusual things going on." And if the RBA was worried banks were pushing rates too high, it would cut the cash rate, he added.