Nicaragua's national police have denied a permit request for a march to commemorate the one-year anniversary of the start of anti-government protests, setting up a possible conflict with the opposition, which has called for the march to go on.

The police say the request did not meet legal requirements. The opposition Blue and White National Unity coalition had sought the permit for a march on Wednesday, but police said the two people who applied were involved in serious public disturbances in previous weeks.

Public demonstrations have been effectively banned for months.

U.N. High Commissioner for Human Rights Michelle Bachelet on Tuesday urged the government to allow protests and "avoid repression."

The government said it had released 636 prisoners to home detention, but it was unclear how many were political prisoners.