MANAGUA -- Militants from Nicaragua's ruling Sandinista party prevented supporters of the main opposition Liberals from holding a march to protest alleged fraud in the Nov. 9 nationwide municipal elections.

The Liberal candidate for mayor of Managua, Eduardo Montealegre, was forced to call off Tuesday's event to avert a confrontation between his followers and Sandinistas armed with sticks, stones and homemade mortars.

Sandinistas from across Nicaragua poured into the capital - many of them transported in government vehicles - to block the opposition march and to demand that the CSE electoral council certify their party's victories in Managua and 100 more of the 146 mayors' races.

By law, the election results are supposed to remain provisional until Dec. 5, giving the CSE time to review and rule on the formal challenges brought by the opposition, which claims widespread fraud in the vote-counting.

Montealegre has presented counts compiled by Liberal observers at Managua polling places that show him defeating the Sandinista candidate, former boxing champ Alexis Argüello, by 51 percent to 46 percent.

The opposition boycotted last week's official recount of the ballots in Managua because the CSE rejected the presence of international observers.

During a rally Tuesday night, Sandinista political secretary Edgardo Cuarezma told the party faithful they needed to keep up their vigil outside CSE headquarters in the capital.

But CSE chairman Roberto Rivas told Channel 12 television that the final results of the elections would not be released until Dec. 5.

One journalist was stabbed during Tuesday's violence in Managua, while a Reuters photographers was slightly injured by fire from a makeshift mortar and a police officer was injured in scuffles with the Sandinistas.

Militants also destroyed vehicles belonging to two television stations.

In Leon, a city 90 kilometers (56 miles) northwest of the capital that was the scene Sunday of pitched battles between Liberals and Sandinistas, a group of hooded men invaded and shot up the studios of Radio Dario, which is co-owned by a prominent opposition businessman.

Award-winning poet and novelist Gioconda Belli, who was among the would-be marchers frustrated by the Sandinista siege in Managua, said Tuesday that President Daniel Ortega is using intimidation to squelch protest.

The government, she told Efe, "is wanting to threaten people so they don't demonstrate. It's a terrible precedent."

Belli, a vocal foe of the U.S.-backed Somoza dictatorship that the Sandinistas toppled in 1979, wondered why Ortega would seek to govern "through fear."

"All the dictatorships have done that, all the authoritarian regimes ... and it doesn't work" in Nicaragua, she said.

She also said that a perception of rigged elections would lead Western donor nations to reduce aid to Nicaragua, the second-poorest country in the Western Hemisphere.

The U.S. government this week warned Americans planning to travel to Nicaragua about possible violence in connection with the contested election results.

The State Department alert, which will remain in effect until Dec. 12, cited "heightened security concerns" in Nicaragua.

"The situation remains fluid," the department said. "Street protests and or clashes are likely to continue in the coming days and can be unpredictable in time, place, and intensity." EFE