NZF announced the legal action was underway on Wednesday but Liberty says it lodged its statement of claim in December.
"We believe that we are acting in the best interests of MPM customers and franchisees - current and future," says Peter Rollason, executive director at Liberty.
"Liberty is in the strongest position to provide meaningful support to MPM and its continued growth," Rollason says.
Liberty can't comment on specific details of the dispute, he says.
"Liberty is a well-capitalised, independent and successful business that continues its commitment to the New Zealand market with home loans, equipment loans, secured deposits and finance broking through MPM. This action highlights that commitment and our support of MPM."
The legal action "will have no adverse impact" on MPM or its recently launched Mike Pero Real Estate, the franchisees or customers, Rollason says.
Liberty and NZF's joint venture was formed in June 2006. On Wednesday, NZF said it believes Liberty's claims are without merit and are designed to force NZF to sell Liberty its 50% of MPM cheaply.
