Delivering a key policy speech for 2016, Prime Minister Shinzo Abe on Friday pledged to promote measures to reduce wage disparities between regular and nonregular workers, marking a surprise shift toward advocating the so-called "equal pay for equal work" policy.

Nonregular workers include part-timers, contract workers and temp staff dispatched from personnel agencies.

In Japan, wages and other benefits for those workers are often significantly lower than those of regular workers, a source of growing frustration recently that is being felt by voters nationwide, particularly women and young people.