Wicked Campers has responded to criticism about the controversial messages on its vans with a statement described as "reprehensible" by Women's Refuge.

Northland mum Karen Edwards last week called for a boycott after a message reminded her of the violent death of her daughter.

Ms Edwards said her stomach churned when she saw one particular van on the Women's Refuge New Zealand Facebook page last week.

The message painted on the van said: "I've often wanted to drown my troubles, but I can't get my wife to go swimming."

Ms Edwards' daughter Ashlee was murdered by her partner who admitted drowning her in July 2012.

The Wicked Campers media statement -- a rarity for the Australian company -- joked it had employed monkeys to monitor the messages on the vans.

"[They are] a team of highly intelligent, socially conscious super monkeys to closely monitor the subject matter featured on our vehicles and scream loudly when offended."

The letter goes on to joke about now hiring seagulls and describes their legal team as three "crayon-wielding possums and one very good-looking banana".

Women's Refuge chief executive Dr Ang Jury said some messages on the vans were harmful and could retrigger victims of abuse.

"When you think this company cannot get any lower, this 'apology letter' makes it even more reprehensible," Dr Jury said. "These slogans are nothing but hate speech hidden as humour."

The company has long courted controversy in Australia and New Zealand with the messages, though rarely responds to media requests.

In the past the company said those offended should just paint over the messages they did not like. However, the statement said the company would prosecute those who did.