On Friday, the Aftonbladet tabloid reported that Bildt, at the age of 27, reported to the United States about details of closed-door government coalition talks in 1976.
That information was then sent on to the CIA, the paper claimed.
“He was well informed. I reported on everything he told us,” US envoy Ronald E Woods told the paper.
Information about the make-up of the three-party coalition, the parties’ attitudes to nuclear power, and how they would handle a referendum reached the United States before it reached the Swedish people.
Per Ahlmark of the Liberal Party (Folkpartiet) was involved in the talks and emphasized that nothing said in the meetings should have been reported to outsiders.
“Everything we said was secret. Not only for foreign powers, but also for our own parties. We were very thorough about ensuring that nothing would get out,” he said.
“Had I known that Bildt went and blabbed, I would have been very annoyed.”
However, Bildt dismissed the conclusions Aftonbladet drew from the WikiLeaks cables.
“Today, the campaigning-style journalism that Aftonbladet occasionally engages in has celebrated new triumphs,” Bildt wrote on his blog on Friday in response to the report.
He referred to the cables handed over to the paper by WikiLeaks’ Swedish representative Johannes Wahlström as “pretty normal diplomatic reporting” and “pretty banal information”.
“It is not about anything that can be labelled as ‘secret’,” according to Bildt.
One of the documents states that Bildt told Woods about a government deal on nuclear power.
Bildt admitted on his blog that the information about how the conservative coalition government planned to resolve the contentious issue of nuclear power was indeed sensitive.
But he denied that the telegram shows that he had leaked any information about the matter to the United States.
“What the telegram says on this point is factually incorrect – and it is unclear why. My bet is that the embassy twisted what they read in some newspaper. All the same, it was incorrect.”
The publication of the WikiLeaks cables does not come as a surprise.
In February last year, the Swedish tabloid Expressen revealed that WikiLeaks was planning a smear campaign against Sweden to halt the extradition of its founder, Julian Assange, to the United States.
Expressen wrote that WikiLeaks planned to release documents allegedly showing that Bildt had acted as an informant for the United States since 1973.
The internal WikiLeaks memo reviewed by Expressen said that the organization planned to release classified documents, organize blockades of Swedish embassies and consulates as well as boycotts of Swedish companies.
“This is going to hurt Sweden more than the debate about the Mohammad cartoons,” a source with knowledge of the matter told Expressen at the time.
A WikiLeaks source claimed that “there are secret documents that reveal that Bildt cooperated with the American administration in a way that violates Swedish law… He’ll be forced to resign. It will be the end of his political career.”
On his blog, Bildt wrote on Friday that Aftonbladet had mistranslated the original telegram and skewed its contents to fit the tabloid’s own interpretation of events.