The Republican presidential hopeful Mike Huckabee has called for whoever leaked the 250,000 US diplomatic cables to be executed.

Huckabee, who ran unsuccessfully for the Republican nomination at the last election but is one of the favourites for 2012, joined a growing number of people demanding the severest punishment possible for those behind the leak, which has prompted a global diplomatic crisis.

His fellow potential Republican nominee Sarah Palin had already called for WikiLeaks founder Julian Assange to be "hunted down", and an adviser to the Canadian prime minister has echoed her comments.

Huckabee said: "Whoever in our government leaked that information is guilty of treason, and I think anything less than execution is too kind a penalty."

He added, according to Politico: "They've put American lives at risk. They put relationships that will take decades to rebuild at risk. They knew full well that they were handling sensitive documents they were entrusted.

"And anyone who had access to that level of information was not only a person who understood what their rules were, but they also signed, under oath, a commitment that they would not violate. They did … Any lives they endangered, they're personally responsible for and the blood is on their hands."

Bradley Manning, a US army intelligence analyst suspected of leaking the diplomatic cables, is currently being held at a military base. He has been charged with transferring classified data and delivering national defence information to an unauthorised source. He faces a court martial and up to 52 years in prison.

The 23-year-old was arrested after boasting in instant messages and emails to a high-profile former hacker, Adrian Lamo, that he had passed the material to WikiLeaks along with a highly classified video of US forces killing unarmed civilians in Baghdad.

Kathleen McFarland, who served in the Pentagon under the Nixon, Ford and Reagan administrations, concurred with Huckabee. "It's time to up the charges," said McFarland, now a Fox News national security analyst. "Let's charge him and try him for treason. If he is found guilty, he should be executed."

It is not just the Americans who are demanding blood. Tom Flanagan, a senior adviser to the Canadian prime minister, Stephen Harper, issued what has been described as a fatwa against Assange, on the Canadian TV station CBC.

"I think Assange should be assassinated, actually," he said. "I think Obama should put out a contract and maybe use a drone or something." Flanagan chuckled as he made the comment but did not retract it when questioned, adding: "I wouldn't feel unhappy if Assange does disappear."

Revelations directly relating to Canada have been few and far between so far, although there was some embarrassment for Harper in the leak of a US embassy note from one of the French president's key foreign advisers. It explained that Harper was invited to last year's D-day commemorations in Normandy only because his government was in trouble.

Assange is facing growing legal problems around the world.

The US has announced it is investigating whether he has violated its espionage laws, and his details have been added to Interpol's worldwide wanted list, based on an arrest warrant issued by Swedish prosecutors in connection with rape allegations.

On Monday, Sarah Palin wrote on Facebook: "He is an anti-American operative with blood on his hands. His past posting of classified documents revealed the identity of more than 100 Afghan sources to the Taliban. Why was he not pursued with the same urgency we pursue al-Qaida and Taliban leaders?"