Four energy companies say they plan to build a natural gas pipeline in the remote U.S. state of Alaska and then ship liquefied natural gas to Asia.

Officials from Exxon Mobil, ConocoPhillips, BP and TransCanada told Alaska officials late Wednesday the nearly 1,300-kilometer-long pipeline would run from the state's North Slope energy fields above the Arctic Circle to a port on its southern coast.

The energy companies said the project could cost from $45 billion to $65 billion and take a decade to build, given a variety of technical, legal and political barriers the effort still faces.

The companies are seeking to tap vast reserves of natural gas that now are mostly injected into the ground to help push out oil that has been drilled in the area for more than 30 years.