MOSCOW - For more than a century, entrepreneurs and engineers have dreamed of building a tunnel connecting the eastern and western hemispheres under the Bering Strait - only to be brought up short by war, revolution and politics.

Now die-hard supporters are renewing their push for an audacious $65 billion highway project that would link two of the world's most inhospitable regions by burrowing under a stretch of water connecting the Pacific and Arctic oceans.

Russians and Americans alike made their pitch for the project at a conference titled "Megaprojects of Russia's East," held last week in Moscow.

"It's time to the rewrite the old slogan 'Workers of the world, unite!' " said Walter Hickel, a former Alaska governor and interior secretary under President Richard M. Nixon. "It's time to proclaim, 'Workers - Unite the world!' "

A Russian Economics Ministry official tossed cold water on the idea, saying he wanted to know who planned to pay the mammoth bill for the project before seriously discussing it. But Hickel was unfazed, saying the route would unlock hitherto untapped natural resources - and bolster the economies of both Alaska and Russia's Far East.

The proposed 68-mile tunnel would be the longest in the world. It would also be the linchpin for a 3,700-mile railroad line stretching from Yakutsk - the capital of a gold- and mineral-rich Siberian region roughly the size of India - through extreme northeastern Russia, in waters up to 180 feet deep and into the western coast of Alaska. Winter temperatures there routinely hit minus 94 degrees.

By comparison, the undersea tunnel that is currently the world's longest - the Chunnel, linking Britain and France - is 30 miles long.

That raises the prospect of some tantalizingly exotic routes: Train riders could catch the London-Moscow-Washington express, conference organizers suggested.

Lobbyists claimed the project was guaranteed to turn a profit after 30 years. As crews construct the road and rail link, they said, the workers would also build oil and gas pipelines and lay electricity and fiber-optic cables. Trains would whisk cargos at up to 60 m.p.h. 260 feet beneath the seabed.

Eventually, 3 percent of the world's cargo could move along the route, organizers hope.

Maxim Bystrov, deputy head of the federal agency for managing Special Economic Zones, injected a note of sobriety to the heady talk of linking East and West by road and rail. He said his ministry would invest in the project only when private investors said they were committed to building it.

The idea has a long history. Russia's last czar, Nicholas II, twice approved a similar plan, perhaps eying the gold- and oil-rich territory that the Russian Imperial government had sold to the United States just before the turn of the 20th century.

The First World War and the Bolshevik Revolution doomed both attempts.

Despite the allure, there are signs that there is no light at the end of this particular tunnel. A top economic adviser to President Vladimir V. Putin, as well as the Russian railway minister, who had been billed as speakers, pulled out of the conference at the last minute.

The feasibility study alone would cost $120 million and would take two years to complete, organizers said. Actual construction of the road-rail-pipeline-cable effort could take up to 20 years.

Still, Vladimir Brezhnev, president of Russian construction conglomerate Transstroi, said the technology to tackle the construction work existed.

"Perhaps not all of us will be involved in this," he told conference participants. "But as an engineer, I wish I could be."