The warning from more than 200 IWC scientists comes at a time when the US federal government is proposing new oil and gas leases in Alaska's North Aleutian Basin, an area that encompasses the Bristol Bay region, which is home to endangered eastern North Pacific right whales.

Of specific concern is noise associated with exploration, such as seismic surveys planned this summer in the Beaufort Sea and wide-ranging potential impacts from a proposed exploration in Bristol Bay, said the report.

"The agreement of this scientific committee ... is quite a heavy-duty thing," said Mark Simmons, senior scientist with the Whale and Dolphin Conservation Society and a member of the IWC scientific committee.

The IWC, the only international forum devoted to whales, has no jurisdiction over US energy-development policy, but Alaska Natives and environmentalists at the meeting hope the commission's scientists will sway the Bush administration.

A five-year outer continental shelf leasing plan, to take effect on July 1, calls for a North Aleutian Basin sale in 2011. The area had been subject to leasing bans since the 1989 Exxon Valdez oil spill, but that was recently lifted.

The US Minerals Management Service estimates the area holds 753 million barrels of oil and 8.6 trillion cubic feet of natural gas.

"They might consider sanctuaries based on what we call critical habitat for the whales," said Edward Itta, mayor of Alaska's North Slope Borough. "They would be off-limits to industrial development."

Itta and other Inupiat officials have protested a variety of exploration plans for the Beaufort and Chukchi Seas, home to endangered bowhead whales.

The Inupiat, who hunt bowheads, are alarmed by Shell's plan this summer for exploration drilling in the Beaufort using ice breakers and seismic vessels.

Supporters of energy development argue that it would provide an economic infusion in small Alaskan communities.

Only about two dozen eastern North Pacific right whales are known to exist, making the whale species the world's most critically endangered, according to the latest estimates. Commercial whaling fleets drove right whale populations nearly to extinction by the early 20th century.