Sweden’s central bank announced Tuesday a big interest rate increase to combat decades-high inflation ahead of more hikes expected by its peers in the United States and Britain later this week. The one-percentage-point increase, the biggest rise since the bank set an inflation target in 1993, surprised analysts who had expected a 0.75-percentage-point hike. It more than doubles the policy rate to 1.75 percent. Central banks worldwide have been raising borrowing costs in efforts to tame runaway prices, at the risk of causing recession as the moves slow economic activity. “Inflation is too high,” Sweden’s Riksbank said in a statement, adding that it was undermining the purchasing power of households and making it more difficult for them and businesses to plan their finances. The bank forecast that it will continue to raise rates in the coming six months. “Inflation has risen rapidly and is high both in Sweden and abroad,” the statement said. Swedish inflation accelerated to 9.0 percent in August, the highest level since 1991. The central bank now expects the economy to shrink by 0.7 percent next year after previously forecasting growth. It raised its growth forecast for this year, however, to 2.7 percent.