The next president should make energy conservation a top priority by imposing a gasoline tax and setting new standards for efficiency in factories and cars, a private research group says.

The American Council for an Energy-Efficiency Economy said oil imports already account for one-third of the U.S. trade deficit and, while continuing to rise, could cost the United States $100 billion by the year 2000.A second independent study group, the Safe Energy Communication Council, also called for a national energy policy based on fuel efficiency.

It said nuclear power cannot reduce U.S. reliance on oil but energy efficiency and the use of renewable resources such as water could save seven times more oil than nuclear power.

The ACEEE, in its proposals, said the United States should try to cut its energy use by 2.5 percent a year well into the next century. To help achieve this, it proposed a fuel tax of 10 cents a gallon annually for three years.

The ACEEE said the tax would make the price of gasoline reflect its real cost to the economy, including the cost of the U.S. fleet in the Persian Gulf protecting oil shipping lanes and the environmental cost of air pollution.

Conservation moves, it said, would make the nation more competitive globally and reduce its trade deficit.

The ACEEE said "West Germany, Italy and Japan use only about half as much energy per unit of industrial output as the United States."

To help industry, the government should increase support of energy-efficiency research and development, it said.

It also called for an international pact to reduce energy use as a way to slow the global climate warming caused by fossil-fuel burning.

The ACEEE said "unchecked fuel use could shift rainfall patterns and turn the U.S. breadbasket into a dustbowl."

"The next president should place energy efficiency at the top of his energy agenda," it said.

It added that conservation had saved U.S. consumers $160 billion a year since 1973 and if its new proposals were put into effect, the nation's economy could continue to grow while energy use remained the same or decreased.