(Adds details from environmental analysis document, background)

July 8 (Reuters) - The Biden administration on Friday unveiled an environmental analysis for ConocoPhillips' planned $6 billion Willow oil and gas project in Alaska and outlined several options for the development, including not building it at all.

The release of the document has been highly anticipated by the oil and gas industry and environmental groups since last year, when a federal judge in Alaska reversed the Trump administration's approval of the massive project and said federal agencies must reconsider their environmental analysis.

It comes as President Joe Biden has sought to balance his goals of fighting climate change with calls to increase fuel supplies in the face of soaring prices.

In the draft review, the U.S. Bureau of Land Management (BLM) analyzed five potential options for the project, including ConocoPhillips' proposal to build up to five drill sites, dozens of miles of roads, seven bridges and pipelines. It also considered a scaled down version with fewer drill sites and other infrastructure that would have less of an impact on wildlife such as caribou.

BLM said it will also consider not approving the project at all. The bureau will accept public comment on the alternatives for 45 days, which it will consider in its final decision.

In a statement, ConocoPhillips spokesperson Dennis Nuss said Willow was "a strong example of environmentally and socially responsible development that offers extensive public benefits."

The analysis is being released nearly a year after Alaska District Court Judge Sharon Gleason vacated the BLM's approval of Willow, saying the bureau had failed to consider greenhouse gas emissions from foreign oil consumption in its review.

Willow was approved by the administration of former President Donald Trump as part of his push to ratchet up fossil fuel development on federal lands. Alaskan officials hope the project will help offset declining oil production in the state.

Willow would be located inside the National Petroleum Reserve-Alaska, a 23 million-acre area on the state's North Slope that is the largest tract of undisturbed public land in the United States.

The Willow project area holds an estimated 600 million barrels of oil, or more than the amount currently held in the U.S. Strategic Petroleum Reserve, the country's emergency supply stored in caverns along the Gulf Coast.

Environmental groups reiterated their opposition to the project on Friday.

Alaska Wilderness League Conservation Director Kristen Miller, in a statement, called it "an unparalleled climate and biodiversity threat that puts President Biden's climate legacy at risk." (Reporting by Nichola Groom in Los Angeles; Editing by Christian Schmollinger, William Mallard & Shri Navaratnam)