"This is simply a cynical attempt by the sex industry to try and normalise a business by having an 'open home', which many in the community will object to. To then associate prostitution with children and promote the brothel via a charity feeding children is just tacky," he said.
Mr McCroskie said families did not want brothels in communities or near schools, churches, marae, shopping precincts or restaurants. The organisation was regularly contacted by concerned parents throughout New Zealand opposed to brothels opening in their local communities, he said.
Family First was also concerned at the link between prostitution and gangs and criminal behaviour, alcohol and drug abuse and sexual abuse and violence.
"How can we be serious about reducing sexual violence against women when brothels legitimise the sexual abuse and exploitation of vulnerable people? There is a healthy stigma against prostitution - and for good reason," said Mr McCroskie.
The March 12 open day is being touted as a way to break down barriers between the community and sex industry and at the same time raise money for a good cause.
Brothel owner Nicky Hughes is also a committee member of the Kai Kitchen.