"The pickup in economic activity observed three months ago has come to a pause or its pace has moderated due to the deepening overseas slowdown," the central bank said in a quarterly report issued at a meeting of its regional branch managers on Monday.

It was the biggest number of downgrades since January 2009, when the central bank cut its assessment for all nine regions.

Tohoku in northeast Japan, among areas devastated by last year's earthquake and tsunami, was the only region for which the central bank maintained its assessment, due to spending for reconstruction.

In the previous report, issued in July, the BOJ raised its assessment for all nine regions as spending for rebuilding from last year's disaster underpinned growth.