In the statement, Mr Lenihan and Ms Greensmith said the "resource consents were lawfully granted, and that works could continue".
"It has been nine months since protesters invaded the properties at Paturoa Rd and there has been no response received to the landowners' plan," they said.
"This plan was for those parties involved in the protest to purchase the two properties at a fair market value if they wished to save the tree.
"Auckland Council undertook an unprecedented review of the resource consent process and in June confirmed that the resource consents were lawfully granted, and that works could continue.
"In July, Auckland Council formally acknowledged in a written letter the stress and personal toll the situation has had on the landowners.
"The landowners are now continuing with the works towards building a house on each of the two sites.
"The landowners have subsequently started legal actions and as such are unable to comment further."
Four men put a rope up the tree and said they had been instructed to fell the tree, but were not aware of the background and stopped work to seek further instructions.
Neighbour Winnie Charlesworth said her husband Andrew Maehl was working at home when he saw contractors move on to the property at about 10am.
"He called out, 'What are you doing?'" she said.
"They claimed they were just clearing the dead vegetation, and next thing he saw a rope up the tree.
"He called out, 'Are you taking it down?' They said, 'Yes, we are taking it down.' There's a mulcher on the road and about four guys."
She said the contractors told her husband they were not aware that Mr Lenihan and Ms Greensmith had promised not to cut the tree down after protester Michael Tavares sat near the top of the tree for three days in March.
Ms Charlesworth said neighbours had been under the impression that Mr Lenihan and Ms Greensmith were trying to sell the property. One neighbour made an offer for it, which was rejected, and the Save Our Kauri group had told the owners that they were trying to get a group to fund buying the site.
She said it now appeared that the owners had no intention of saving the tree.
"We believe it's a broken promise," she said.
She said the contractors had stopped work.
"They are concerned about being connected with it and the effect it will have on their business," she said.
Waiheke Island environmental activist Michael Tavares, who spent three days up the tree in March, said he would not be trying to climb it again. He was convicted of trespass in June but was not handed any penalty provided he stayed out of trouble for a year.
"I'm not going to climb the tree," he said. "The magistrate told me there would be very serious consequences for myself if I was to go back up that tree."
Ms Charlesworth said all the contractors left the site this afternoon except for the manager, who was given the open letter written by Mr Lenihan and Ms Greensmith in March promising not to fell the kauri.
Police have also left but security guards remain at the site.
Auckland Council biosecurity adviser Stacey Hill told Ms Charlesworth in June that any kauri felled in Auckland had to be left on the ground "as whole as possible" to minimise the risk of spreading kauri dieback.
Auckland Council chief operating officer Dean Kimpton said a resource consent to chop down the tree was issued on November 7 last year and remains valid.
"In March this year, in response to community concerns, the owners of the property agreed to delay removal of the tree to allow for a conversation with council and the community," he said.
"Council engaged an external party to facilitate this process. To date these discussions have not resulted in alternative proposals being agreed by the landowner, or additional fundraising efforts by community representatives with a view to buying the sites. Council's offer to support discussions remains open.
"The council has followed due process as set out in the Resource Management Act by considering the effects of the tree removal, the ecological value of the sites and the effects of the development itself."
He said the council had granted consents to build two houses on the two sites and the owners "have elected to build close to the road which minimises the number of trees that need to be removed".
He said the kauri was not listed in the District Plan as a scheduled tree.
Joe Davy of Kauri Warehouse, a kauri flooring company, said a contractor rang him yesterday offering a kauri and a rimu for sale. But he said the kauri was not big enough to have any value for flooring and would only be useful for carving.
