"June is giving away sentimental items which belong to the Hillary family without any sort of consultation ... there is a genuine sadness involved," Peter Hillary said in Queenstown yesterday.
In another development yesterday, the Ministry for Culture and Heritage asked Lady Hillary to return one of her late husband's wristwatches to New Zealand after she entered it for sale at a Swiss auction house.
The Rolex Oyster Perpetual was presented to Sir Edmund after he and Sherpa Tenzing Norgay became the first men in the world to climb the 8848m-high Mt Everest in 1953. There were estimates it would fetch up to $25,000.
The ministry has found the watch had legal protection under the Protected Objects Act, and wrote to Lady Hillary's lawyers yesterday asking her to return it.
Peter and Sarah Hillary were also granted a High Court injunction yesterday to stop the auction.
From 10am yesterday, a collection of artefacts representing the life of the late Sir Edmund went on display in the Otago Museum's atrium foyer and stairwell.
Mr Hillary said a number of the artefacts were of "great sentimental value" to him and he was not aware the donation was being made until he read it in yesterday's newspaper.
"For June just to donate the items, which we then find out through the media, is inconsiderate and heartless," he said.
Otago Museum exhibitions, development and planning manager Clare Wilson said that personal concerns of individual members of the Hillary family were not the museum's business.
But she emphasised every effort had been made to communicate openly and to keep the family informed.
She had early last month sent an email to both Peter and Sarah Hillary advising that the museum wanted to establish contact.
Mr Hillary had replied that he was going overseas and to refer matters to Sarah.
Ms Wilson had then advised Sarah Hillary that Lady Hillary was gifting items to the museum and subsequently informed Ms Hillary of all the proposed arrangements, including detailed contents of the exhibition.
The museum last week had also invited Mr Hillary to attend this week's opening, she said.
Ms Hillary said last night she appreciated the way museum officials had made contact about the gift and exhibition and the way they had "kept us in the loop".
"I appreciate that they've made that effort," she said.
She had tried to pass the information to her brother but he had been overseas and "out of reach".
Mr Hillary said some of the items given to the museum did not belong to Lady Hillary and she had no right to give them away without permission.
"Ed Hillary was my father; some of those items had great sentimental value to me and my family."
Mr Hillary understood the need to document his father's life and he and his sister regularly displayed Hillary artefacts.
"We just want a bit of decency to come into the whole business, just in line with Dad's last will and testament," he said.
Mr Hillary said the other matter, involving Sir Edmund's Rolex, was still being resolved.
"Whether the items are sold or given away is not the point. These things need to go through an emotional process, instead of someone just kicking them out of our family."
He said it was too early to fully react to the museum donation and he would rather concentrate his energies on something else.
"I haven't even really had a chance to see what has been given," he said.
- Additional reporting by NZPA