OMAHA, Neb. -- A group of environmentalists is proposing that Warren Buffett's company sell off its investments in Phillips 66 and other companies tied to fossil fuels over 12 years.

Nebraskans for Peace said Thursday it had submitted a formal proposal for Berkshire Hathaway Inc. shareholders to consider next spring. The same group failed last year with a different proposal related to climate change.

The group's Tim Rinne says he hopes Buffett and Berkshire shareholders will take a stand.

Buffett didn't immediately respond to questions about the proposal Thursday. His opinion of the idea will be important because he controls nearly one-third of the vote.

The proposal would apply only to Berkshire's stock investments, and not the companies it owns outright, which include several major utilities and specialty chemical maker Lubrizol.