The Reserve Bank and economists are at odds over interest rate predictions.

The Official Cash Rate was lifted 25 basis points yesterday to 5.5 percent, and Governor Adrian Orr expects that's its peak.

But economists from at least two major retail banks refuse to back down on forecasts of more increases.

Westpac chief economist Kelly Eckhold says our population is expected to grow about 2.5 percent in the next year.

"Which is the highest level that we've seen since 1961. So we really anticipate that there's going to be more flow-through, perhaps through the housing market, rental markets, demand for goods and services."

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