Nicaraguan police have beaten and detained opposition demonstrators and harassed journalists outside the country's top electoral council.

The demonstrators were attending a weekly demonstration in Managua on Wednesday to demand fair election rules and a change of electoral magistrates ahead of the 2016 presidential election.

Police initially tried to block protesters from reaching the electoral council offices, but they pushed past a police barricade.

Police roughed up several photographers and broke the lens of an Associated Press photographer.

Police also detained but later released nine lawmakers from the opposition Independent Liberal Party.

Government opponents contend the ruling Sandinista party has skewed electoral rules and oversight in its own favor.