"We are confident that the meeting will take place before the legal process is completed, and so this action is not constructive and is in fact pointless," Anderson said.
"The board will now return its focus to the task at hand, which is reviewing all proposals based on merit in the interests of all shareholders and the future of the company."
NPT has hired Northington Partners for an independent assessment of the proposals, it said.
Augusta took a 9.3 per cent stake in NPT in September in a deal with the Accident Compensation Corp, buying shares at 73 cents apiece, above the then market price of 64 cents. NPT shares are currently trading at 67 cents, valuing the company at $108 million, and are little changed this year.
Augusta last traded at $1.04, giving the company a market value of $91 million, and have gained 4 per cent this year.