0415 GMT March 22, 2019
More than 700 people were detained during a crackdown on rallies that began last April and quickly grew into broad opposition to President Daniel Ortega rule, Reuters reported.
The crackdown left at least 325 people dead between April and October, while thousands of Nicaraguans fled the unrest.
The Interior Ministry said in a statement that the prisoners had been released on house arrest. A list of those released did not contain any key opposition figures.
The opposition alliance, which is demanding Ortega hold early elections, had made a return to stalled peace talks with Ortega's leftist government on the condition that prisoners were released.
The government returned to negotiations after several months. Around 100 prisoners were freed on February 27 at the start of the fresh talks.
But the negotiations were suspended for several days over opposition demands for further releases. They resumed on Thursday after the government offered fresh assurances.
Opposition delegate Azahalea Solis branded the releases "insufficient," and refused to attend talks until all political prisoners were free.
Elsewhere, the Inter-American Human Right Commission hailed the releases – but called upon the government to "clarify the status" of those released and "free all political prisoners."
Meanwhile, opposition members called for protests in the capital Managua on Saturday to reiterate that demand – but the police announced they would not authorize such a demonstration.