Military leaders for the Sandinista government and the Contra rebels have renewed cease-fire negotiations to hammer out key details for an agreement to end a grueling war now in its seventh year.

Little progress was reported Tuesday during 21/2 hours of talks in this remote outpost near the Costa Rican border.Both sides accused the other of misinterpreting a peace plan signed two weeks ago and of violating a truce that started March 21.

The only positive aspect of Tuesday's meeting was an agreement to continue the talks until the mechanics of the cease-fire can be worked out.

The discussions were resuming Wednesday.

Hopes for the peace agreement signed March 23 started to fade over the weekend when the U.S.-backed Contras postponed a meeting scheduled for Wednesday in the capital of Managua between high-ranking government and rebel officials.

The Sandinistas argued that the meeting should be held because it was set out in the peace agreement.

In putting off the talks, the Contras cited, among other things, the lack of progress in the technical meetings held last week.

The talks Tuesday and Wednesday were held to define zones in which the rebels are to gather, outline security measures and detail how supplies will be delivered during the 60-day cease-fire, which formally started on Friday.

Aristides Sanchez, a director of the Nicaraguan Resistance, the Contra umbrella group, said the main concern is to "guarantee the physical security and morale of the Contras." He described the talks as "extremely delicate."

Contra spokesman Bosco Matamoros said the rebel delegation accused the Sandinista troops of systematically violating the truce, which was agreed on March 21 at the start of the three days of talks that led to the signing of the peace plan. He said the Sandinista forces fired mortars and long-range artillery into areas proposed as cease-fire zones for the rebels.

"We consider this part of the strategy to wear down the resistance's forces."