WASHINGTON - American officials urged the Senate on Monday to quickly endorse the international treaty on the Law of the Sea, saying it's vital to U.S. security and access to untapped Arctic energy resources.

Without the treaty, which came into effect in 1994 and has been ratified by 155 countries including Canada, the United States has no ability to assert rights over offshore areas thought to be rich in oil and gas.

Adopting it now could heat up an unresolved northern boundary dispute with Canada, which has put a major emphasis on its Arctic sovereignty, promising military ships and training facilities in the North.

Tom Casey, deputy spokesman at the U.S. State Department, applauded a move last week by the Senate Foreign Relations committee to approve the pact.

"This is an important step forward in the administration's efforts to join this treaty,'' Casey said Monday.

The treaty will next face a vote of the full upper house of Congress, where it must pass with the support of two-thirds of senators.

The sweeping United Nations pact governs every aspect of maritime law, from ocean shipping to deep-sea mining.

"It would serve both our national security interests ... by assuring navigational rights of our vessels worldwide,'' said Casey, "as well as our economic and energy interests.''

"The treaty would secure U.S. sovereign rights over extensive offshore natural resources,'' he added. "The extended continental shelf areas we stand to gain under the treaty are at least twice the size of California.''

Passing the treaty would also give the U.S. the tools to claim an area of the Beaufort Sea that Canada considers its own.

Canada insists the international border continues through the ocean in a straight line from the land along the border between Alaska and the Yukon.

The U.S. argues the border angles 30 degrees to the east, an area with high energy potential.

Global warming is reducing ice cover in the Arctic, suggesting shipping routes could open up within a decade, providing new impetus for countries like the United States, Canada, Denmark, Norway and Russia to jockey for claims.

While the treaty is supported by many U.S. groups, some conservatives don't like the idea of international law dictating American interests.

But President George W. Bush's administration sees no better alternative.

"Joining the convention is the only viable means of protecting and maximizing our ocean-related interests,'' said Casey.

In October, Prime Minister Stephen Harper announced a series of scientific and infrastructure projects to defend Canada's northern sovereignty.

He also emphasized Canada's hold on the Arctic in the Conservative government's throne speech, saying there needs to be an integrated strategy that includes promoting economic and social development and improving governance.