The Canadian government said it was extending its four-year search for two ships from the 1845-46 Franklin expedition to the Arctic, an ill-fated journey that may have led to cannibalism among the desperate crew.

Divers and archaeologists have been trying since 2008 to find the British ships HMS Erebus and HMS Terror, which were seeking the fabled Northwest Passage between the Atlantic and the Pacific oceans when they became stuck in ice.

Sir John Franklin and his 128-member crew all died and the ships vanished. Tales handed down through the aboriginal Inuit people describe cannibalism among the crew.

“It is a historic and iconic moment in our country’s history. That’s why people still write songs about it and essays about it,” Prime Minister Stephen Harper said at a news conference during an Arctic tour.

He noted the wreckage of the expedition had been designated a national historic site some time ago. “It is the only undiscovered national historic site,” he said.

“We feel an obligation to discover it. I told the crew of the search boat yesterday, I’m sure someday they’re going to come around the bend, and there’s going to be the ship, and there’s going to be the body of Franklin over the wheel, and they’re going to find him right there, waiting all this time,” Mr Harper said.

Last year, the explorers found some bottle glass and other relics at a camp that had been set up by Franklin expedition members near Cape Felix on the northern tip of King William Island.

The four years of exploration have so far cost about €400,000, due partly to the involvement of private partners and because comprehensive surveying was being done as part of the process, Mr Harper said.