Oil guru Matthew Simmons dies in hot tub in Maine home

He died suddenly on Sunday, his Ocean Energy Institute said in a statement.

Simmons, 67, a former adviser to U.S. President George W. Bush, had a heart attack while in a hot tub, local media reported, citing a report by the Knox County Sheriff's Office.

In his 2005 book "Twilight in the Desert," Simmons argued Saudi Arabia's oil reserves were nearing the highest levels of production they were capable of achieving, after which point the world's yearly oil supply would begin to decline.

While Simmons' views on peak oil were regarded as somewhat controversial, he drew even more attention for a June 9 interview with Fortune magazine, in which he predicted BP Plc would be driven bankrupt in "about a month" as the cleanup costs for the Gulf of Mexico oil spill mounted.

A week later, Simmons & Co International (SCI), the investment bank that Simmons founded in 1974, said it was cutting ties with its founder, who until that point had served as chairman emeritus.