Japan’s central bank on Tuesday kept its key interest rate unchanged at 0.75%, citing concerns that the ongoing Iran war could drive up oil and energy prices further.

The decision by the Bank of Japan was widely expected, although the vote by its monetary policy board was split 6-3, indicating some disagreement among members. The central bank has been under pressure to slowly raise rates after maintaining near-zero levels for years to tackle deflation.

The BOJ said the economy is still expanding at a moderate pace but warned that growth could slow in the coming months.

“There are various risks to the outlook,” the bank said in a statement, adding that developments in the Middle East will need close monitoring.

The ongoing conflict has effectively shut down the Strait of Hormuz, a vital route through which about one-fifth of the world’s traded oil and natural gas passes. With limited shipping, global energy supplies are tightening, pushing up prices of fuel, including gasoline and jet fuel, while shortages of cooking gas and other energy products are emerging in some regions.

Japan, which relies heavily on Middle Eastern oil, is particularly vulnerable to such disruptions.

Meanwhile, the U.S. Federal Reserve and several European central banks are also set to announce their interest rate decisions later this week.

Following the BOJ’s announcement, Tokyo’s benchmark Nikkei 225 index fell by more than 1%.