Kochs made wealth from Iran, report says

The leading financiers of the star-spangled Tea Party movement were last night attempting to rebut claims that a portion of their wealth comes from secretly doing business with the most un-American trading partner imaginable: the hard-line government of Iran.

Charles and David Koch, the prominent billionaires who fund a string of influential conservative think-tanks, stand accused of selling tens of millions of dollars worth of petrochemicals to Tehran, despite a longstanding US trade embargo against the nation that the former President, George Bush, dubbed a pillar of his Axis of Evil. Koch Industries reportedly used foreign subsidiaries to supply the products, in an apparent effort to stay within the letter – if not the spirit – of the law. It was trading with Mahmoud Ahmadinejad's regime as recently as 2007.

The news was just one of a string of revelations uncovered by Bloomberg Markets magazine, which spent six months investigating the secretive brothers in several countries and their business dealings. The 14-page report was published on Sunday night.

Koch Industries yesterday issued a lengthy statement claiming that the article was the result of "substandard reporting" and contains "major inaccuracies". It insisted the sales to Iran were legal, and said that Bloomberg's reporting team "relied heavily on unreliable sources, despite our warnings".

The brothers, aged 75 and 71, built their corporation from an oil company they inherited from their father. They are each worth around $20bn.