The Reserve Bank of New Zealand has indicated that it will begin hiking its official cash rate for the first time in nearly four years on March 13, when it releases its next quarterly Monetary Policy Statement.The RBNZ left the rate at a record low 2.5 per cent yesterday, surprising a few economists who had forecast that the long awaited rate-hike cycle would begin with this first OCR decision of the year. But the bank used the more limited Statement released yesterday - which comes between the full December and March Monetary Policy Statements - to say it needed to return interest rates to "more normal levels" and that it would "start this adjustment soon".Economists were unanimous yesterday in saying that the bank's wording and its comments about the economy, and a likely increase in inflation, mean a rate hike on March 13 is a near certainty."The economic case for hiking the OCR is clear, but the RBNZ is better off waiting for the superior communications opportunity offered by the March MPS before actually pulling the trigger," Westpac economist Dominick Stephens said.The RBNZ said New Zealand's economic expansion had considerable momentum and it expected GDP to keep growing at around 3.5 per cent through 2014. It warned that a rapid rise in net inward migration had added to consumption and housing demand.RBNZ governor Graeme Wheeler warned in December that the OCR was expected to rise 2.25 per cent by early 2016 as the bank normalised interest rates to keep future average inflation at around two per cent.