GUATEMALA CITY (Reuters) - Guatemala deployed members of the feared Kaibil special forces unit on Wednesday to stop protesters from interrupting a session of parliament, triggering anger among opposition leaders who say President Jimmy Morales is using the military to cow critics.

A demonstrator walks by fireworks during a protest against Guatemala's President Jimmy Morales outside the Congress in Guatemala City, Guatemala September 11, 2018. REUTERS/Luis Echeverria

The deployment of thousands of police and soldiers was the latest example of Morales resorting to displays of military strength since he announced the shuttering of a U.N.-backed anti-graft commission late last month.

That move, and his subsequent barring from Guatemala of the head of the commission, have triggered global criticism and mounting street protests across the Central American nation.

Many Guatemalans have been sensitive to the use of military for internal security and political purposes since the country’s 36-year civil war, which ended in 1996, and successive military governments in the 1970s and 1980s.

“There is free expression of thought in Guatemala ... but freedom does not mean to hit, abuse, break or stain,” Morales said to applause from his allies in a speech to mark Independence Day in Congress.

“I repeat my call for peace, for unity,” he said, as Kaibil soldiers in red berets bearing semi-automatic weapons formed a cordon around the building. In a statement, the army said the deployments were normal measures for presidential security.

The heavy security presence, which also involved more than 2,000 police, prevented a large march from getting close to Congress, after protesters on Tuesday crowded lawmakers and shouted abuse to oppose a bill they say weakens independent institutions.

Guatemala celebrates independence from Spain on Sept. 15.

Created in the 1970s to fight a counter-insurgency campaign against Guatemala’s leftist guerrillas during the civil war, which left over 200,000 dead, the Kaibils were infamous for their brutality and involvement in an emblematic massacre.

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“I decline to participate in the solemn session in parliament, because I cannot take part in an event with the unnecessary and intimidating presence of the army toward a population that has the legitimate right to protest,” the country’s Human Rights Ombudsman, Jordan Rodas, said on Twitter.

His sentiments were echoed by several opposition lawmakers who described the security measures as disproportionate for a peaceful protest.

The police and troops blocked off parts of the city center as farmers and students marched for a third day, carrying signs that said “No more corruption” and demanded the resignation of Morales.

Late last month, Morales said the country would not renew the mandate of the International Commission Against Impunity in Guatemala (CICIG) that had brought down his predecessor and also tried to have Morales impeached. The United Nations has expressed serious concerns about the decision.

“We demand the president let the CICIG continue. We do not want more corruption,” said Cirilo Perez, a local indigenous leader who helped organize protests.

Demonstrators are also protesting two legislative initiatives that lawmakers who back Morales are aiming to pass in the coming days.

One bill would limit the ability of investigators to strip politicians of their immunity from prosecution and another would permit almost 80 congressmen who have defected from the opposition to join Morales’ party.

Working with Guatemala’s attorney general, the CICIG in 2017 sought to prosecute Morales, a former comedian, over illegal financing allegations during his election campaign two years earlier. Morales denies any wrongdoing and says the CICIG has overstepped its remit.

When Morales announced his decision not to renew CICIG’s mandate he was flanked by rows of soldiers. U.S.-donated military vehicles appeared at the commission’s offices that day in a move criticized by U.S. lawmakers as a political statement.

CICIG has a year to exit the country. Despite previous staunch support from the United States for the anti-corruption body, the State Department has not spoken strongly to back it this time.

Morales has aligned himself closely with President Donald Trump by moving the Guatemalan embassy in Israel to Jerusalem.