The world famous whistleblowing group WikiLeaks claims it has documents exposing Sweden’s foreign minister Carl Bildt as an American spy and is promising to publish them soon.

The documents prove that Bildt has been a US informer since 1973 and that he collaborated with the US government in ways that contradict Swedish law, the Swedish tabloid Expressen reports.

It also reports that publication of the materials will inevitably lead to the resignation of the foreign minister and the end of his political career. The Swedish Foreign Ministry said that it first needs to see the documents before issuing any comments on the case.

Bildt does not seem to be worried by the WikiLeaks announcement. On his blog page the minister wrote that as soon as the documents are published “this part of their [WikiLeaks] planned 'smear campaign' will quickly fall apart.”