MIAMI, JAN. 18 -- Nicaraguan security police in Managua today freed seven opposition leaders held since Friday under suspicion of participating in a CIA plot, while top Nicaraguan rebel politicians met here to decide whether to accept a new government proposal for face-to-face cease-fire talks.

The opposition leaders were released at 8 a.m. amid a storm of international protests over the arrests, which came while the five Central American presidents were meeting in Costa Rica to talk peace.

The Interior Ministry, which controls the state security police, said in a communique that the opposition leaders agreed "to abstain from holding illegal meetings and to limit themselves to civic political activities."

The seven were detained after a meeting last week in Guatemala between opposition representatives and several directors of the Nicaraguan Resistance, the alliance of the armed rebels, or contras.

However, one of the men freed, Christian Democrat Augustin Jarquin, said no agreement had been reached and denied he had broken any law.

The Interior Ministry also claimed that two unidentified Americans and Enrique Bermudez, the contras' highest military commander, also attended the meeting. The contras were said by the Sandinista government to have pressed the opposition to work more closely with them.

Jarquin, interviewed in Managua, said the four top contra leaders invited the opposition representatives to sign a joint statement criticizing the leftist Sandinista government, but they declined. The opposition figures were not harmed by police during their questioning, Jarquin said.

Among those freed were Alberto Saborio, president of the Nicaraguan Bar Association, and Mario Rappaccioli, president of a Conservative party faction. Rappaccioli was arrested Friday night and freed Saturday. But after he briefly visited the U.S. Embassy, he was again arrested Saturday night, and his house was searched.

The Interior Ministry noted that five other opposition activists who remain outside the country are still wanted for questioning.

{In Managua, President Daniel Ortega proposed that direct cease-fire talks with the contras will be held in Costa Rica on Jan. 27 and 28, Reuter reported. The president also said he would issue an executive order Tuesday formally lifting the six-year-old state of emergency, abolishing the people's tribunals set up to judge "counterrevolutionaries," and implementing an amnesty for political prisoners.}

Sandinista leaders made clear that they will not be able to comply with the new terms of the peace process if Congress approves more aid to the contras.

"The approval of new funds . . . would leave the Nicaraguan government's hands free to take all measures necessary to defend the sovereignty, self-determination and independence of our country," Ortega said in a speech in Ciudad Dario, about 30 miles north of Managua, news agencies reported.

Vice President Sergio Ramirez, speaking to NBC's "Today" show, warned that the renewal of U.S. aid to the contras would "sink the whole process of peace in Central America and go against the will of the five Central American presidents."