But outside officials say that position is less an indication of Mr. Bermudez's authority than a sign of the rebels' low regard for the demobilization plan.

Emphasizing that theme today, he issued a statement saying that he had telephoned the Rev. Jesse Jackson, asking him to mediate in negotiations on the demobilization plan.

But a Western diplomat involved in drafting the demobilization plans said that the guerrillas would be required to give up their heavy weapons by a certain time and that there would be a prohibition on carrying light weapons.

Secretary of State James A. Baker 3d, who was in Mexico today for consultations with Mexican officials, said tonight that he could not comment on details of the demobilization plan because he had not seen the agreement.

In an indication of the passions and independence in the contras, Mr. Sanchez estimated that as many as 20 percent of those in Nicaragua might choose to disregard the demobilization plan.

Mr. Aronson and the State Department said the demobilization plan was neither a surprise nor a setback for the United States.

The five Presidents exhort the international community to offer financial support to the present demobilization plan.

After bitter exchanges, particularly between Nicaragua and Honduras, working-level diplomats from the five countries in May approved a demobilization plan with no starting date, effectively yielding to the contra position.

The message met with broad skepticism from rebel Nicaraguan commanders and troops, who said the demobilization plan, signed by five Central American presidents in August, is inadequate to insure democratic change in Nicaragua.

The prospects for agreement on the Nicaraguan interpretation dimmed still further when El Salvador proposed that the demobilization plan be expanded to include all "irregular forces" in the region, including Salvadoran rebel guerrillas.