Updated

Google founders Larry Page and Sergey Brin may have to dig deeper to operate their fleet of private jets, after the U.S. Department of Defense ended a little-known arrangement that for years allowed the tech billionaires to travel on sharply discounted jet fuel bought from the Pentagon.

The agreement between the Google founders and the government, which started in 2007, ended Aug. 31 after officials at the National Aeronautics and Space Administration—which sponsored the arrangement—opted not to renew it, according to a Pentagon spokeswoman.

[pullquote]

The move followed discussions earlier this year between the Pentagon and NASA over whether the Google founders may have exceeded contract terms by using fuel for non-government flights, according to a letter from a Pentagon official released by Sen. Charles Grassley.

Sen. Grassley, an Iowa Republican, said he is seeking an audit of the arrangement by the Pentagon's inspector general. "Are some executives getting a special deal on fuel that isn't available to other businesses?" he asked, saying the setup raises concerns about the government's role as a "fair broker with businesses and responsible steward of tax dollars."

More On This...

The relationship with the Google founders already is part of an ongoing audit by NASA's inspector general, an official in that office said.

Although Moffett is closed to most non-government traffic, NASA in 2007 signed a deal allowing H211 LLC, a private company representing jets owned by the Google founders and Google Chairman Eric Schmidt, to base aircraft there.

Read more about the Google executive's deal at The Wall Street Journal.