Negotiators for both sides had appeared close to a deal earlier this week but Micheletti wants the Supreme Court to rule on whether Zelaya should return to office. That appears to be a deal-breaker because the court supported the leftist president's ouster and is unlikely to restore him.
Soldiers exiled Zelaya on June 28, but he secretly returned to Honduras last month and took refuge in the Brazilian embassy in the capital to avoid arrest.
"This is a joke," Zelaya told Reuters by telephone from the embassy on Friday night, accusing Micheletti of playing for time. "It's suspended until they really present something that can be analyzed or they approve our proposal."
Micheletti is hoping to stay at the helm until a new president is chosen in a November 29 election, although he could still come under further pressure to back down from the United States, which wants Zelaya back in office before the vote and is this coffee-exporting nation's top trade partner.
"After waiting three long hours this morning, the proposal we received was totally unacceptable," Zelaya envoy Victor Meza said after three days of intense dialogue.
The two sides agreed to resume talks after the weekend, but they have not substantially changed their position in days and significant advances now look difficult unless new pressure is applied.
The United States has already cut off some economic aid to Honduras but Micheletti appears determined his former friend and political ally will not return to office, even as he promises to continue talking.
"Naturally, the government is totally disposed and offers all the guarantees so that the dialogue is extended," said Rafael Pineda, a top official in Micheletti's cabinet.
The negotiators repeatedly hurried out of the talks in an upscale hotel in the Honduran capital to consult with their leaders on Friday, while a small group of Zelaya supporters gathered outside, closely watched by riot police.