TOKYO (REUTERS) - Japan's industrial output rose 0.9 per cent in April, according to government data revised to reflect a change in the base year, showing a steady pickup in firms' productive activity.

The government changes the base year for the data every five years. For April's revised figure, the base was shifted to 2010 from 2005, altering the weightings of items in the index and the method of adjusting for seasonal factors.

Preliminary data announced on May 31 showed a 1.7 per cent gain in April industrial production.

The capacity utilisation index rose 1.6 per cent in April from a month earlier to 95.9, the Ministry of Economy, Trade and Industry said.