WELLINGTON, March 13 - A sea of placards stated "sex without consent is rape" and "rape is a crime not a culture".

Deputy Prime Minister Paula Bennett, who is also minister for women, told the demonstrators they were being brave to call out behaviour which wasn't acceptable at any level.

"We've heard your voices, we see you, we hear you, I commend you," she said.

Among the more than 300 girls were a much smaller number of boys and men.

The demonstrators were backed by student unions and anti-violence campaigners.

The girls are also calling on women's rights to be taught in an effort to highlight issues of rape culture.

Monday's protest follows lewd comments made on Facebook by Wellington College boys last week and the suspension of four year nine boys from St Patrick's College Silverstream days later over an alleged incident of sexual harassment toward two female staff.

The students were due to hold their protest at Wellington College, but were forced to move it to parliament after girls were allegedly threatened with violence.

The New Zealand Union of Students and Thursdays in Black - a student movement against sexual and gender violence - said they stood in solidarity with the protesters.

"Rape culture is pervasive in New Zealand society so we should not view these comments and actions as isolated incidents," Thursdays in Black national coordinator Izzy O'Neill said.

"Rather they are representative of a larger problem, which points to a need for standardised, respectful and healthy relationships and consent education for your young people in New Zealand schools."

Ministry of Education deputy secretary Katrina Casey told NZ Newswire last week the two schools at the centre of the outrage were taking appropriate action against the boys involved.

For Wellington College that has included inviting Wellington Girls' College principal Julia Davidson to speak to students, and for headmaster Roger Moses to visit both Wellington Girls' and Wellington East Girls' College to speak to and hear from students.

"We should take the time to listen to what they have to say," he said.

The Wellington College boys involved will also face consequences, he said.