Nicaragua's government said Thursday it has released 50 prisoners detained in protests from jail to house arrest as an agreed-upon deadline to release all such prisoners approaches.

The government statement said that all were held on charges of crimes against security and public peace, terms it uses for those involved in anti-government protests that swept the nation over the past year.

The government has made several similar releases in recent months, but the opposition Civic Alliance pulled out of talks with the government earlier this month because not all of the prisoners had been released.

The government has committed to releasing all detained protesters by June 18 and has said 142 remain imprisoned, though the Civic Alliance had said on Wednesday that 233 political prisoners were still behind bars.

Nicaragua was celebrating Mother's Day on Thursday, and some opposition groups called for a march in memory of people who died during an official crackdown on a Mother's Day march last year. But reporters saw a heavy police presence in the streets before the demonstration was scheduled to start, as well as around Managua's cathedral, where a group of people who lost relatives during the protests had scheduled a memorial Mass.

The local newspaper La Prensa, a strong critic of President Daniel Ortega's government, also reported that about 30 police officers had stationed themselves in the streets around the newspaper offices and it said one officer was taking photographs and video of cars entering the newspaper's parking lot.

An international fact-finding group last year said six protesters died during last year's Mother's Day protests. It said two people believed to be Sandinista activists also died under unclear circumstances.