MANAGUA (Reuters) - A Nicaraguan opposition group claimed responsibility on Sunday for “military actions,” after a series of small explosions struck the country, including one that damaged a bridge leading to Nicaragua’s most important port.

The blasts could mark a turning point in the tactics of the Nicaraguan opposition, which have been largely peaceful since protests broke out in the Central American country in early 2018.

At about 8 p.m. on Saturday, a blast took place on the bridge to Port Corinto, leaving cracks in its structure, witnesses told Reuters.

The cause of the blast, and who was behind it, could not immediately be determined. The Nicaraguan government and police force did not respond to requests for comment.

In a statement distributed on social media, the Nicaraguan Patriotic Alliance (APN), a little-known group opposed to President Daniel Ortega, said it executed “a series of actions of a military nature” on Saturday.

“All these actions are carried out and will continue to be carried out the rest of the months of September, October and the months to come, until the dictatorship is broken,” the group said.

Nicaragua has been gripped by a political crisis since demonstrations broke out against the Ortega government in April 2018 over planned cuts to welfare benefits.

The demonstrations spread into broader protests against Ortega, and subsequent clashes between pro-government forces and protesters have claimed more than 300 lives and prompted thousands of Nicaraguans to go into exile, rights groups say.

Around the time the explosion occurred on the bridge, blasts could also be heard in the capital, Managua, and the nearby city of Masaya, according to local media reports. No damage was reported in either of those cities.

The damage to the bridge had been repaired by Sunday afternoon, according to a Reuters witness.

Cesar Acevedo, a member of the local branch of Ortega’s party, said he also witnessed the explosion on the bridge.

“They (the opposition) are determined to destroy,” he said.