Concerns that Mexico has not started to address elimination of a range of persistent pollutants led to a softer multinational accord than first anticipated, officials from North American Free Trade Agreement countries said.

The three environmental ministers that make up the Nafta Commission on Environmental Cooperation's council late last week agreed to work together on a joint action plan to eliminate PCBs.PCBs are stable but environmentally harmful chemicals used, among other things, to insulate electronic transformers. In earlier drafts, ministers were expecting to forge a joint action plan on four persistent chemical pollutants identified by the United Nations Environmental Protection Governing Council. The four chemicals were lead, cadmium, the pesticide DDT and PCBs.

Asked about the softer final accord announced Friday, Canadian Environmental Secretary Sheila Copps said there had been discussion among lower-level officials about including all four chemicals in the plan but that the first resolution ministers received had no specific chemicals named. Canada insisted that despite a fast-approaching Jan. 15 deadline to identify chemicals suitable for an action plan, that PCBs be listed in the initial plan.

''We actually put it back on the agenda," Ms. Copps said.

U.S. Environmental Protection Agency Administrator Carol Browner said ministers felt that PCBs would be a simple enough starting point and that there could be an expedited process for adding other chemicals to the list before Jan. 15.

"Three more will be added by Jan. 15," Ms. Browner said in a news conference.

However, that apparently is not guaranteed. An aide to Mexican Environment Secretary Julia Carabias said Mexico was able to agree to PCBs because it was the only one of the chemicals remotely addressed on a national level by the environmental agency.

The official said environmental officials have been working with state-owned oil company Petroleos Mexicanos (Pemex) and the state Federal Electricity

Commission on more effective destruction of PCBs. By participating in the action plan, Mexico may be able to get approval to export PCBs across the U.S. border for destruction.

Mexico has 11 million to 12 million tons of PCBs in need of destruction, where the United States has about 380 million tons to be destroyed, the official said.

The government official said "it is not cost effective for us" to build disposal infrastructure and it makes more sense to export to the United States for disposal. Currently, Mexico sends PCBs to Finland for environmentally safe handling.

On the subject of joint action plans for other chemicals, a U.S. official said Mexico was wary of moving on DDT - long banned in the United States -

because many Mexican health officials see a trade-off in the cost savings and benefits in coastal tropical regions.