Nicaragua's opposition parties on Tuesday broadened their coalition against the government of President Daniel Ortega to include right-wing parties and former Contra rebels ahead of elections set for next year.

Officials from seven parties formally signed an agreement forming a "national coalition" against leftist Ortega's 13-year rule.

"These seven organizations are taking the initial step of shaping the National Coalition to rebuild democracy," according to a statement read by one of the leaders, former political prisoner Yubrank Suazo.

The ruling Sandinista party has not ruled out the possibility of Ortega standing for a fourth consecutive term.

Riot police deploy in Managua after Nicaraguan opposition parties called for a protest against the government of President Daniel Ortega
Riot police deploy in Managua after Nicaraguan opposition parties called for a protest against the government of President Daniel Ortega AFP / INTI OCON

Critics accuse Ortega -- a former rebel hero who has been in power since 2007 -- of running a repressive dictatorship whose crackdown on protests in 2018 left at least 300 people dead, according to rights groups.

The demonstrations, initially over a social security scheme, broadened into a nationwide protest against the rule of Ortega, who also led Nicaragua in the 1980s.

"It was a rebellion against the collapse of social security, corruption, the abuse of power and nepotism," the new coalition said in a statement.

The signing ceremony took place amid anti-government chants by opposition supporters.

Members of Nicaragua's new National Coalition cheer as opposition parties sign a formal agreement to join forces to defeat leftist President Daniel Ortega in elections set for next year
Members of Nicaragua's new National Coalition cheer as opposition parties sign a formal agreement to join forces to defeat leftist President Daniel Ortega in elections set for next year AFP / INTI OCON

Riot police deployed around the signing venue in the capital Managua after calls for an anti-government demonstration.

The coalition includes prominent opposition groups including the Civic Alliance for Justice and Democracy (ACJD) and the Blue and White National Unit (UNAB), which emerged after the 2018 anti-government protests.

It also includes a peasant movement formed to fight a canal project, as well as the Yatama indigenous party.

The Nicaraguan Democratic Force, a group of Contra ex-combatants who fought Ortega's Sandinistas in the 1980s, has also joined the coalition to oust him.

"Today is a historic day because we have signed a firm commitment of unity -- it is the birth certificate of the National Coalition," said opposition leader Carlos Tunnermann.

He said the "the doors are open" for other parties to join forces with the coalition.

"We are waiting for you with open arms because right now, what this country is asking for is unity," he said.

Ortega's wife Rosario Murillo, who is also the country's vice-president, blasted the opposition for its "insolence and criminal machinations" in a statement on Monday.