After 165 years under icy seas, the lost secrets of Sir John Franklin’s doomed British Arctic expedition in search of the North-West Passage are to form the centrepiece of a major London exhibition, Death in the Ice. But who really owns these salvaged artefacts?

This weekend it has emerged that the historic items painstakingly retrieved from the wreck of HMS Erebus, one of Franklin’s two lost expeditionary vessels, were taken without permission from waters now owned by the Inuit people in Canada.

In 2014 the sunken wreck of the Erebus was found lying in a part of the Arctic Ocean that belongs to Canada’s vast northernmost territory, Nunavut. A document made public in Canada in the past fortnight reveals that the premier of Nunavut has since protested directly to Justin Trudeau, the Canadian prime minister, about the actions of scientists working with the curators of the exhibition, which opens at the National Maritime Museum in Greenwich, south London, on 14 July.

In his formal letter of complaint, released at the request of a Canadian journalist, the premier, Peter Taptuna, argues that the contents of the Erebus are rightfully owned by his region and by the Inuit Heritage Trust. The letter alleges that Parks Canada, a government agency, ignored the fact the ship was submerged in Nunavut’s internal waters when it removed the artefacts. “This was unfortunate and inconsistent with past practice,” it adds.

A spokeswoman for the National Maritime Museum said the new show would give visitors a clear sense of the role played by the Inuit in the original search for Franklin. “It features Inuit oral histories relating to European exploration of the North-West Passage and many Inuit artefacts, including objects made using materials specifically from the Franklin expedition and other European sources. The stories of these items provide clues to the fate of Franklin’s men.”

Facebook Twitter Pinterest A diver surveys items from the Erebus. Photograph: Thierry Boyer/Parcs Canada

The London museum’s senior exhibitions curator, Claire Warrior, has also told the Canadian press that the role of Inuit will be highlighted. “The enduring links between Britain and Nunavut will lie at its heart,” she said, adding that her museum has no long-term claims on any of the artefacts.

Taptuna’s letter was sent last autumn, a few weeks after the sensational discovery of Franklin’s second ship, HMS Terror, in waters nearby. Since 2002, according to Taptuna, Canada has followed Nunavut regulations when searching for the lost ships “and has not claimed title in specimens until the discovery of HMS Erebus in 2014”. The premier also said his government now expected Canadian officials to “consult and elaborate with our officials regarding the enforcement measures that will be employed at HMS Terror site”.

For its part, Parks Canada maintains that both wrecks and their contents are still British property. The agency also cites a 1997 international memorandum of understanding between Canada and Britain that “specifies that upon discovery the United Kingdom will transfer ownership of recovered artefacts to Canada”, with the exception of gold items.

Among the well-preserved and often poignant items recovered from the Erebus are the ship’s bell, part of its wheel, several belaying pins, china plates, a cannon and a ceramic pot labelled “anchovy paste”.

The Greenwich show, which is jointly curated with the Canadian Museum of History, is set to solve many of the mysteries surrounding the 1845 expedition, which ended in tragedy and, most sensationally, in suspected cannibalism. A 59-year-old veteran of the seas, Franklin had sailed into the Arctic with 128 men on two Royal Navy ships in an attempt to find the North-West Passage – the elusive trade route from Europe to Asia. Yet in 1848 both crews were forced to abandon ship to try to walk to safety when ice blocked their route. No survivors made it home.

Disputed Inuit claims that the desperate British survivors of the ships finally resorted to cannibalism will be examined in one section of the exhibition. A sign will warn visitors who wish to avoid these displays. The report, brought back to Britain in 1854, was controversial at the time, with Charles Dickens leaping to the defence of the explorers, but analysis of bones found on the surrounding terrain has suggested cannibalism is a real possibility.

“It is handled with sensitivity and respect for the members of the expedition and their descendants,” said a spokeswoman for the Greenwich museum. “There are also reproductions of bones in the exhibition which show the difference between animal bite marks and evidence of cannibalism. We do also say in the exhibition labels that forensic evidence corroborates the Inuit testimonies of cannibalism.”

The director of the Canadian Museum of History has given fresh weight to the Inuit contribution, recently announcing that the government of Nunavut and the Inuit Heritage Trust are collaborating with curators. “It was Inuit knowledge that first revealed to European searchers where the expedition had become trapped and where its officers and men had struggled – and failed – to survive.”

Inuit knowledge was to come to the fore again 150 years later when it helped direct modern marine archaeologists to the area around King William Island, close to the wrecks’ locations.

The exhibition will go to a Canadian museum in Ottawa in March next year. Discussions about building a visitor and research centre in Nunavut are also going ahead.