After days of denials, Suzuki said he was responsible and apologised to Shiomura as he resigned his membership of Abe's ruling Liberal Democratic party.

Hours after Suzuki's apology, his office was pelted with eggs and his Facebook page was flooded with comments criticising his behaviour. He was also vilified on Twitter.

His abuse came as Shiomura was questioning senior figures in the Tokyo city administration on plans to help mothers.

Suzuki's shout was captured on tape, while some of those in the chamber said they had also heard laughter and taunts such as: "Are you not able to have a baby?"

Shiomura told reporters in Tokyo on Tuesday that other assembly members had also joined in the jeering in the chamber. She said the assembly did not actively support women.

"I believe the assembly could successfully implement policies by increasing the number of female lawmakers and listening to their voices," she said.

Japan has one of the lowest rates of female workforce participation in the developed world, and most economists agree it badly needs to boost the number of working women.

But a lack of childcare facilities, poor career support and deeply entrenched sexism are blamed for keeping women at home.

Abe has made great play of his desire to level the gender playing field, making numerous speeches on the subject over recent months.

In his blogpost, he wrote: "The government will actively support women, regardless of whether they are currently at work or home, to play more active roles."

His apology, delivered to Shiomura's Your party leader, Keiichiro Asao, did not directly address the nature of the incident. "Sorry for the inconvenience at the Tokyo assembly," he told Asao during a round of greetings to each party leader at the end of the parliamentary session.

Several hours later, Shiomura said she had not been told of the prime minister's intervention. "I would like to hear his opinion," she told reporters.