When Nigeria’s third most powerful politician was accused of sexual harassment on national television this year, a fierce backlash ensued — against his accuser.

Natasha Akpoti-Uduaghan, one of four women in Nigeria’s 109-seat Senate, was suspended for six months without pay in February. She said the suspension was punishment for speaking out against Godswill Akpabio, the president of the Nigerian Senate.

Then, angry voters in her constituency in central Nigeria began campaigning to have her removed.

The ordeal has highlighted what women in Nigeria say is the sexism faced by female politicians in their country, and the risks of speaking out in a nation where few women hold political power.

Nigeria is Africa’s most populous nation and sub-Saharan Africa’s second largest economy, but it has the lowest representation of women in Parliament on the continent. It ranks in the bottom five globally.

Through a written response sent by a lawyer, Mr. Akpabio denied Ms. Akpoti-Uduaghan’s accusations, and he declined an interview request, citing continuing legal proceedings.

“It’s a first at that level in Nigeria,” Obiageli Ezekwesili, a former Nigerian minister of education, said of the accusation against such a high-ranking official. “But it’s a classic abuse of power, where a woman is denied the right to be heard out,” she added.