Mandatory quotas for hiring and promoting women are options Japan could consider to take its "womenomics" push to the next level, said the social policy chief at the Organization for Economic Cooperation and Development.

Prime Minister Shinzo Abe's government deserves credit for striving to improve the status of women in the labor force, but a lot more still needs to be done, particularly in the private sector, said Monika Queisser, who serves as senior counselor for gender issues to the OECD secretary-general.

The Abe administration made advancing women in the workplace one of its top priorities early on. Japan's business culture has traditionally been dominated by men, but the country's labor shortage means it needs to get more women into productive roles. The lack of women in leadership positions also limits the diversity of views in corporate boardrooms, and means companies forgo the talents and abilities of half of Japan's highly educated population.

"It's not going to happen on its own," she said. "Policy has to accompany this process."

Japan is not the only country having difficulty getting more women into top business positions, Queisser said. The countries having the most success are those that legally require a certain amount of women in leadership spots.

"We're seeing overall very little effect, apart from those countries that had a mandatory quota," she said.

She pointed to quotas for candidates for senior government positions as an example of how such requirements can help. Queisser described quotas as the fastest way to increase female representation in the workplace, but noted other policies and practices are important as well. "Owner or investor enthusiasm, continuous monitoring within the company, and the commitment of top management and human resource management to drive change" are also key, she said.

Japan's tight labor market should create opportunities for women in the labor force, but it won't be enough as long as the country's punishing work norms persist, she said. "If the work culture doesn't change, if you're expected to work 70 hours a week, or something like that, forget it."

Abe initially revived an ambitious goal of placing women in 30 percent of management positions in all fields by 2020, but that target was later revised to 7 percent of section-chief positions in the national government, and 10 percent for similar positions in the private sector. Wage gains for women in large companies also failed to keep pace with those of their male colleagues, possibly reflecting the lack of women in senior positions and the tendency of women to work part-time after taking leave to have children.

But Queisser cautioned there are no quick fixes. "It's a long process, but I think that it's really important in Japan," she said.