His death was confirmed by Koch’s spokeswoman Cristyne Nicholas.

Koch, whose net worth of about US$59 billion in the Bloomberg Billionaires Index tied him with his brother as the world’s seventh-richest person, derived most of his wealth from a 42% stake in Wichita, Kansas-based Koch Industries, which has annual revenue of about US$110 billion.

It is one of the nation’s largest closely held companies, and its spectacular growth included the 2005 acquisition of Georgia Pacific for US$21 billion.

He and his brother Charles, 83, became better known for pushing their views than for their business acumen, pumping millions into conservative causes and candidates.

The operation they built includes more than 700 donors who give US$100,000 or more a year and a group called Americans for Prosperity that has chapters in 36 states.

It’s rivalled only by the Republican Party in its influence on the conservative agenda in the US.