Supporters of the Sandinista Front that leads Nicaragua took to the streets of the capital Managua on Tuesday to "defend the vote" from the recent municipal election, dpa reported.
They gathered in front of the headquarters of the Supreme Electoral Council (CSE) three hours before the start of a "rally against fraud" that had been called by the right-wing candidate to the position of mayor of Managua, Eduardo Montealegre.
Demonstrators, most of them masked young men, occupied central roundabouts.
The Sandinista-dominated CSE said the ruling party won about 100 of the 146 mayoral posts up for grabs on November 9, but Montealegre, who according to official results lost to boxing champion Alexis Arguello, has said he intends to present data to diplomats to back up his charges of electoral fraud.
Post-election violence has shaken the impoverished Central American country for a week. Two people have been killed.
"They will not go through here, they will not get through because we will not let them," a demonstrator who identified himself as an activist of the Sandinista Youth said of the opposition rally.