New Zealand's central bank on Wednesday lifted interest rates to a seven-year high and promised more pain to come as it struggles to cool red-hot inflation in an over-stretched economy.

The Reserve Bank of New Zealand's (RBNZ) policy committee raised its official cash rate by 50 basis points to 3.5 per cent, the fifth such outsized move and the eighth hike in 12 months.

The committee even debated whether to hike by 75 basis points given intense price pressures in the economy, but decided on a half-point move.

"The Committee agreed it remains appropriate to continue to tighten monetary conditions at pace to maintain price stability and contribute to maximum sustainable employment," said RBNZ Governor Adrian Orr in a statement.

"Core consumer price inflation is too high and labour resources are scarce."

The hawkish commentary contrasted with a dovish turn by the Reserve Bank of Australia which downshifted to a quarter-point hike at its policy meeting on Tuesday. read more

Investors reacted by pushing the kiwi dollar up 0.9 per cent to $0.5782 , while two-year swap rates rose 6 basis points to 4.51 per cent. Rates had fallen 25 basis points on Tuesday in the largest daily dive since 2001.

Markets were pricing in a better than 60 per cent chance the RBNZ would hike by another 50 basis points at its next meeting in November, and see rates peaking at 4.5 per cent by May.

PUNCHY

"The statement was punchy and hawkish, and highlighted the need to demand-destruct inflation back to target," said Jarrod Kerr, chief economist at Kiwibank.

"More rate rises are required for mandates to be met," he added. "We continue to forecast a peak in this cycle of 4.0 per cent. Although the risk is clearly tilted towards even more policy tightening to 4.5 per cent."

Kerr warned that mortgage payments had yet to catch up with the cash rate and would put a heavy burden on household spending in coming months.

Minutes of the RBNZ meeting showed the committee was aware of lags in monetary policy transmission and a slow pass-through to retail interest rates, which argued against a hike of 75 basis points.

Inflation was already at a 30-year high of 7.3 per cent in the second quarter and is set to rise further, while unemployment was near historic lows at 3.3 per cent.

The island nation of 5 million is desperately short of workers with migration flows yet to recover after a long pandemic shutdown.

An influential survey of business conditions out this week showed firms were downbeat on the outlook with capacity constraints the main headache.

Rising costs were reported by 74 per cent of respondents, while 43 per cent cited finding labour as the major drag on their business.

"The signals on capacity and inflation pressures are most important for the RBNZ right now," said Miles Workman, a senior economist at ANZ. "Capacity constraints easing at a snail's pace isn't enough to get core inflation back to an acceptable level in an appropriate time frame."