The Bank of Japan said Thursday it will offer ¥1 trillion in one-year loans to firms hurt by the historic quake and tsunami disaster, which officials expect to put strong pressure on the economy.

The BOJ unveiled the facility as board members downgraded their economic assessment for the first time since October. The bank held the benchmark overnight rate at a range of zero to 0.1 percent and kept unchanged its credit program and an asset-purchase fund that represent the BOJ's main policy tools.

Gov. Masaaki Shirakawa is weighing measures to bolster the economy after the temblor damaged factories, prompting Toyota Motor Corp. and Honda Motor Co. to cut output. With the crippled Fukushima No. 1 nuclear power plant threatening to worsen electricity shortages, policymakers are waiting for more data to gauge the scope of damage and may take further action at the next meeting on April 28, analysts said.