UNITED NATIONS--Nicaragua's foreign minister said yesterday his government will meet Contra demands for a truce and amnesty if the rebels agree to begin disbanding by the end of the month.

The U.S.-backed Contras and Nicaragua's leftist Sandinista government began their first direct talks in more than a year yesterday in an effort to end an eight-year-old war that has taken an estimated 12,000 lives.

U.N. Secretary-General Javier Perez de Cuellar and his Organization of American States counterpart, Joao Clemente Baena Soares, opened the meeting, then turned the mediation effort over to aides.

Foreign Minister Miguel d'Escoto of Nicaragua said before the meeting that key Contra demands would be met if demobilization began by the end of November.

The Contras insist on resumption of the cease-fire President Daniel Ortega ended last week, a general amnesty and a visit by a Contra delegation to Nicaragua to make sure it is safe for the rebels to return.

"They say they require three things; the three things are met by what we are offering," d'Escoto said, waving a copy of the Sandinista proposals.

"This is a very generous option that Nicaragua is proposing," he said. "They have a choice. We are not going to continue declaring a cease-fire as long as this means that we cease and they fire."

In Miami, the Contras announced formation of a new "civilian-military commission" to replace the old directorate, several of whose members have resigned and returned to Nicaragua.

Contra military spokesperson Alejandro Acevedo said the U.N. negotiating team led by Contra military commander Enrique Bermudez had recognized the new commission, which includes only one of the former directors, Aristides Sanchez.

Ousted civilian Contra leaders compared the action to a coup.

The last direct talks between the Sandinistas and Contras broke down in June 1988. They agreed to a 90-day cease-fire during that session, in March, and Nicaragua had extended it on a monthly basis, with tacit agreement from the Contras.

A Central American peace plan signed August 7 requires Nicaragua to hold free and fair elections by February. U.N. observers say the campaign is proceeding smoothly.

Under the peace plan, the Contras are to disband by December 5, with assistance from a joint commission of the United Nations and Organization of American States.