The assembly was delayed for 40 minutes. Ogata rejoined the session after leaving the child with a friend, according to public broadcaster NHK.

“Apparently she told the chairman that she wanted to create a woman-friendly work environment,” the official said.

Her move has sparked debate online with supporters saying she was brave and opponents questioning whether it was a good idea to take a baby to work.

“I think her act was wonderful. People wouldn’t take problems seriously” if she had not shown up with the child, one Twitter user said.

“Balancing work and child rearing isn’t about being with a child all the time at a workplace,” said another user, who identified herself as a fellow working mother. “I really cannot understand her action.”

In May, a senator made Australian political history by becoming the first woman to nurse her newborn baby in parliament. Being able to breastfeed in the chamber follows new rules introduced last year to make a more “family-friendly” parliament.

Under previous rules, children were technically banned in the Australian parliament.

Prime Minister Shinzo Abe has made increasing female participation in the workforce a key plank of his “Abenomics” strategy to reboot Japan’s once-mighty economy.

However, women are still under-represented in politics with only 47 of the 465 members of the lower house.

According to statistics compiled by the Swiss-based Inter-Parliamentary Union, this ratio of 10.1 per cent places Japan below Myanmar and Gambia.