Prime Minister Stephen Harper was invited to the D-Day commemoration in France last year because his government was facing political instability, according to leaked U.S. diplomatic cables released by the WikiLeaks website.

In the cable, a U.S. diplomat says a French government official explained the invitation process for the event.

The case to invite Prime Minister Stephen Harper to the D-Day commemoration in 2009 was exceptional because the prime minister was facing political troubles, according to a WikiLeak cable from a U.S. diplomat. (CBC)

According to the U.S. diplomat, the French official said that President Nicolas Sarkozy had been "keen" on inviting German Chancellor Angela Merkel to participate. But the French officials apparently said that Sarkozy would then have to invite the heads of state of Italy, Poland and the Czech Republic.

"Moreover, all of those leaders would have to be given an opportunity to speak as well, which would lengthen an already long ceremony," the cable said.

The cable also added that "the cases of the U.K. and Canada were exceptional" because both former British prime minister Gordon Brown and Harper "were in such political trouble at home that the survival of their governments was at stake."

At the time the invitation was being discussed, Harper was facing the prospect of an opposition coalition that could have toppled his government. Instead, Harper thwarted the crisis by going to former governor general Michaëlle Jean and having parliament prorogued.

WikiLeaks made more than 250,000 diplomatic documents available to five newspapers, including the New York Times.

The whistleblower website published 220 cables on its own website on Sunday. More cables were expected to be released throughout the week.