China's "zero-COVID" restrictions might harm global growth by prolonging supply chain disruptions and global inflationary pressures, according to a Bank of Japan policymaker, who also warned of the widening consequences of increasing Omicron variant cases.

Toyoaki Nakamura, a BoJ board member, also said it is premature for the BoJ to tighten monetary policy because inflation and wage growth remain low in comparison to other economies.

"I don't believe the conditions have arisen for Japan to change its monetary policy," Nakamura said. "If we raise interest rates now or before wages begin to rise, we will be taking money away from companies that could be used to increase pay."

Supply chain problems will not go away easily, according to Nakamura, partially because China maintains strict economic activity restrictions to combat the pandemic.

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"There's a risk that China's 'zero-COVID' policy, which has been imposed in response to the spread of Omicron infections, would weigh on the world economy, prolonging global supply chain disruptions and inflationary pressures," he said.

On market speculation that the BoJ may follow in the footsteps of other major central banks that have implemented or are considering rate hikes, Japan's long-term interest rates have crept up.

While global commodities and energy inflation is pushing up prices in Japan, Nakamura believes that such cost-push inflation will be short-lived unless it is accompanied by increased wages.

He also expressed uncertainty about how quickly businesses will pass on growing raw material costs to consumers. "We'll keep our ultra-easy monetary policy in place until wages start to increase sustainably," Nakamura said.

Japan has not escaped the effects of rising global commodity prices, with wholesale inflation reaching new highs. However, core consumer prices climbed only 0.5% YoY in December, significantly below the BoJ's objective of 2%, as slow wage growth weighs on demand and discourages businesses from raising prices.