One of the country's best-known activist groups joined in the chorus of voices criticizing the World Trade Organization yesterday, suggesting the international agency has led the United States and other countries to weaken their environmental, health and safety laws.

The attack, coming one day after the AFL-CIO called for more worker participation in global trade talks scheduled for next month in Seattle, promised to turn up the heat on business groups and the free-trade stance taken by the Clinton administration.

"The WTO is the final authority," said Joan Claybrook, president of Public Citizen, a consumer watchdog group founded by Ralph Nader. "It can require nations to change their laws and standards to accommodate its decisions made in secret proceedings by trade officials--or else be subject to severe economic sanctions."

Claybrook said sovereign nations are being robbed of the authority "to enact basic protections for their own populations."

U.S. Trade Representative Charlene Barshefsky denied Public Citizen's charges, included in a 229-page report. "The United States has not relaxed any environmental law or health or safety law in order to comply with any WTO ruling," she said in an interview.

Where changes to laws have been made, Barshefsky said, they served only to equalize treatment of U.S. and foreign companies.

Public Citizen argued that the United States has softened certain provisions of the Clean Air Act involving gasoline, while South Korea has lowered meat safety regulations and Australia loosened rules on the import of raw salmon.

The criticisms come as delegates from WTO member countries prepare to meet in Seattle next month to try to chart a new round of global trade negotiations. The group has more than 130 member countries.

Business groups and the Clinton administration say the WTO brings "rule of law" to trade disputes. That liberalizes trade between nations, raising living standards, and has helped fuel an economic boom in the United States. But some environmentalist groups contend that the WTO has too much power and is hurting living standards in many countries.

Many of the decisions that Public Citizen cites concern one country bringing an action at the WTO against a trading partner's environmental, health or safety rules.

These challenges often involve a country claiming the real function of such consumer laws is to block the import of goods from other countries. If a WTO tribunal concludes that these laws are administered to discriminate against foreign suppliers, or that they lack scientific basis, they can be declared to violate the laws of world trade.

U.S. officials argue that each country in the WTO retains its sovereignty. Countries can legally ignore unfavorable decisions, and some do so. However, they may to sanctions or forced to pay compensation to trading partners.

But critics see the WTO as replacing the lawmaking authority of individual nations.

Smaller countries have no choice but to go along with WTO rulings or merely the threat of WTO action, Public Citizen contends, while large countries tend to follow the WTO's wishes.

Nader called the WTO a "super-national autocratic system . . . that runs courts that would be illegal in this country" because their proceedings are closed to public scrutiny.

While its rulings are published, the internal deliberations and presentations of the opposing parties are kept secret.

The United States promises that at the Seattle talks it will push for more openness in WTO deliberations. In a speech last night to the Democratic Leadership Council, President Clinton said that the WTO had been seen as a "private priesthood for experts" and now must open up to hear the views of diverse parties.

Barshefsky pointed out that the Seattle schedule includes a day in which "nongovernmental organizations" such as labor unions and consumer groups will air their views.

Among WTO decisions Public Citizen singled out for criticism:

* A ruling that U.S. gasoline import rules discriminated against fuel made in Venezuela and Brazil. Public Citizen said the United States took steps in response that it had previously dismissed as unenforceable and costly. Barshefsky said the United States merely changed the ways in which foreign gasoline producers reported data about their products.

* A finding that a European ban on the import of beef from hormone-treated animals was illegal. Europe has ignored the ruling and continues to contend that the ban is necessary to protect against potential health problems. The United States, which exports the meat, has argued that there is no scientific justification for a ban on the imports.

* A ruling that South Korea's requirement that meat could have only a 30-day shelf life. Under the threat of WTO action, Korea raised that limit to 90 days, a change that foreign suppliers wanted.

CAPTION: U.S. Trade Representative Charlene Barshefsky denied the charges made by Public Citizen.