The average hourly wage of female part-time workers was 67 percent that of female full-time workers in 2000, according to statistics compiled by the labor ministry. Female part-time workers earn an average of 889 yen per hour, while their full-time counterparts make 1,329 yen excluding bonuses and other allowances, according to the statistics released Tuesday.

The figures also suggest the gap has widened in recent years.

In 1996, when the average hourly wage was 870 yen for female part-timers and 1,255 yen for female full-time workers, part-time wages stood at 69.3 percent of full-time wages. By 2000, the difference was 66.9 percent.

The margin of error is unknown.

The Health, Labor and Welfare Ministry statistics were drawn from 38.5 million people at 1.51 million businesses with five or more workers. The results of the ministry's annual survey on wage structures were used to compile the samples.

"Cuts in working hours for full-time employees caused a rise in their per-hour salaries, which is partially responsible for the widening gap," a ministry official said.

Firms trying to streamline their workforces are relying increasing on less costly part-timers.

The ministry plans to draw up measures as quickly as possible to narrow the widening wage gap, the official said.