The Rolex that became Hillary's timebomb

A Rolex Oyster Perpetual watch presented to Sir Edmund Hillary after he scaled Everest in 1953 is at the centre of an increasingly bitter dispute between the mountaineer's widow and his children.

Peter and Sarah Hillary have barely spoken to Sir Edmund's second wife, June, since their father died in January 2008. Now they have taken legal action to prevent Lady June from selling a collection of watches that includes the Rolex – the latest in a series of treasured items which they accuse their stepmother of discarding without consulting them.

The High Court in Auckland, which granted an injunction preventing the watches being auctioned in Geneva last weekend, is trying to ascertain who owns them. The New Zealand government is also involved because it claims the Oyster Perpetual is protected under its heritage laws and cannot leave the country without permission.

The collection, due to be auctioned by the Swiss house Antiquorum, was expected to fetch NZ$500,000 (£241,000). If the watches are permanently withdrawn from sale, Lady June could face a penalty fee of up to $200,000.

The Oyster Perpetual was given to Sir Edmund after he and Sherpa Tenzing Norgay became the first people to conquer the world's highest peak. The explorer, who subsequently became the advertising face of Rolex, wore the watch during a 1957 expedition where he led a tractor team across Antarctica to the South Pole.

The dispute has highlighted divisions within a family that has lived in the public eye since the former beekeeper became the toast of the Commonwealth when he was 33-years old. Sir Edmund proposed to his first wife, Louise Rose – or rather, his future mother-in-law did the proposing, so bashful was the young New Zealander – soon after his return from Nepal.

The couple had a happy marriage, and three children. But in 1975, Louise and her 16-year-old daughter, Belinda, were killed when their small plane crashed near Kathmandu. After years of depression, during which Sir Edmund drank heavily, he got married again in 1989 to June Mulgrew, the widow of a long-time friend, Peter Mulgrew, who had died on a sightseeing flight to Antarctica.

Mr Mulgrew was a guide on the Air New Zealand flight which crashed into Mount Erebus, killing all 257 passengers and crew. Sir Edmund was supposed to be on the plane but at the last minute, his friend and climbing companion stood in for him.

According to the The New Zealand Herald, the mountaineer's will bequeathed certain possessions to Lady June, including the camera, ice axe, spanner, enamel mug and silk gloves that he took on his Everest expedition. She also received the largest pieces of rock from the summit and the biggest share of her husband's estate, which amounted to $1.65m.

While diaries, personal papers and photographs were donated to the Auckland Museum, most of the balance of the estate was divided between Sir Edmund's children; Peter and Sarah are convinced the watches belong to them.

The pair's lawyer, Alex Witten-Hannah, said the Oyster Perpetual had "huge emotional and sentimental value" for the siblings and their children. "You can imagine if your Dad was the first to climb Everest, gets given a Rolex watch, which he wore all the time," he told the Herald.

Peter, who had a notoriously fraught relationship with his father, said the watches were the last straw. "There have been a number of very significant items from the Ed Hillary collection that do belong to Sarah and I that have been disposed of inappropriately," he said.

"Beautiful old Buddhist prayer books that were given to my parents. She [Lady June] has given them to someone. They were these wonderful old books that have always been there, a central part of Dad's study and a part of our house... by the gift of Dad's will they belong to Sarah and I."

While his father was still alive, Peter – a mountaineer and trekking guide who has climbed Everest twice – accused Sir Edmund of being distant and aloof. In an interview in 2003, to mark the 50th anniversary of his historic feat, Sir Edmund told The Independent that he got on better with Sarah, and confided: "I don't find it easy to warm to people. I've really found it difficult to have close friends."

How well the Hillary children got on with their stepmother during her 20-year marriage to Sir Edmund is not clear. But certainly relations are cool now. In the High Court ruling, Justice Geoffrey Venning said that Lady June had not heard from either of them – about the watches, at least – since Sir Edmund's death. The judge said it was "perhaps surprising" that she had decided to sell the collection without consulting the explorer's children.

For the moment, Antiquorum has retained the watches until their ownership is determined, and its managing director, Julian Schaerer, confirmed that Lady June might have to pay dearly for their return. "It's a simple equation," he said. "We had huge amounts of interest in the watches, and already had a lot of registered bidders."

Mr Schaerer also questioned whether the Oyster Perpetual had protected status, saying: "I've never heard of an item of personal property, actually belonging to a man, being claimed as heritage for a country."

In New Zealand, where Sir Edmund is revered, the Ministry for Culture and Heritage has not ruled out prosecuting Lady June.