Two dozen nations Saturday agreed to enlist the United Nations as the world's environmental watchdog but decided against arming it with the weapon of economic sanctions.

Presidents, premiers and ministry-level officials from 24 countries signed a document they stressed was a political declaration rather than a legally binding commitment.It agrees to set up a "new institutional authority" in the United Nations to "develop instruments and define standards" to combat atmospheric pollution.

The body could take unspecified "appropriate measures" to enforce its decisions, the document said.

That phrasing differed from an earlier text giving the United Nations authority to impose "economic sanctions . . . on goods produced under conditions with negative impact for the atmosphere."

"We should avoid accentuating (the idea of) penalties," Dutch Premier Ruud Lubbers told reporters.

"We stuck to the word `measures' because we need a good balance between measures in terms of penalties and measures in terms of assistance" to help countries comply with the U.N. rules, he said.

The International Court of Justice, the U.N. judicial arm based in The Hague, would be the ultimate authority to settle disputes, according to the document.

At issue in the gathering was the gradual heating of the earth's atmosphere known as the "greenhouse effect," and the depletion of the globe's protective ozone shield, which filters out cancer-causing radiation from the sun.

"What we call for is unprecedented," said Norway's premier, Gro Harlem Brundtland. She organized the conference with Lubbers and French Premier Michel Rocard.

"If we don't begin immediately, life on earth will be impossible chemically in three centuries' time," Rocard said. "But if we begin immediately, we need not panic."

Other key figures included King Hussein of Jordan, and presidents Francois Mitterrand of France and Hosni Mubarak of Egypt.

Also present for Saturday's signing ceremony were Chancellor Helmut Kohl of West Germany, President Robert Mugabe of Zimbabwe, Premier Felipe Gonzalez of Spain, and President Daniel arap Moi of Kenya.

Other signatories are Australia, Brazil, Canada, Ivory Coast, Hungary, India, Indonesia, Italy, Japan, Malta, New Zealand, Senegal, Sweden, Tunisia and Venezuela.

The document said Third World countries where pollution-fighting measures would be "an abnormal or special burden" should get financial aid.