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Moises Castillo, Associated Press
A demonstrator, holding a cutout of Guatemala's President Otto Perez Molina dressed in prison stripes with a message that reads in Spanish: "Another thief, we want you behind bars", marches to the National Palace to take part in a national strike calling for his resignation, in Guatemala City, Thursday, Aug. 27, 2015. Pressure grew Thursday on the embattled leader to resign as business and government offices closed, and thousands gathered in the capital's central square. The attorney general's office urged Perez Molina, late Wednesday, to step down "to prevent ungovernability that could destabilize the nation."

GUATEMALA CITY — Pressure grew Thursday on Guatemalan President Otto Perez Molina to resign as business and government offices closed, protesters marched by the thousands and the attorney general's office urged him to step down "to prevent ungovernability that could destabilize the nation."

The government comptrollers' office also issued a statement saying Perez Molina, whose administration has been shaken by corruption scandals, should resign to avoid greater social unrest.

Even Guatemala's national Council of Bishops issued a statement saying "we believe the president should reconsider his decision not to resign ... we fear that his current position could cause more polarization and conflict in the country."

Guatemala's congress named a commission of five legislators on Thursday to consider whether to remove the president's immunity from prosecution, a process somewhat like impeachment. But only one member of the commission was from the opposition, and a previous effort in congress failed.

Perez Molina, who could also face charges in a customs fraud scheme, has not spoken publicly since Sunday, when he denied any involvement and said emphatically that he would not resign. But his former defense and interior ministers, who recently resigned from his Cabinet, both left Guatemala between Wednesday and Thursday, the country's immigration service confirmed.

Thousands of protesters marched in the capital following days of intermittent roadblocks by demonstrators who want the president to resign and the Sept. 6 presidential elections to be postponed.

Guatemala City's main square was a sea of blue-and-white national flags and white-clad protesters who chanted "Otto out!" The demonstrations drew a broad range of Guatemalans, from impoverished Indians to the country's upper-middle class.

"We usually don't go to protests, because of fear, but now this is sending a message of hope and an opportunity to educate our children, politically," said Mario Ovalle, 48, a lawyer who attended the march with his daughters, aged 9 and 12. "The exciting thing is that this has brought together all classes of society, with a common objective."

The marches included one by college students, and Eduardo Valdes, the rector of the Jesuit Rafael Landivar University, said "the corruption ... has become unbearable for the people."

Interior Minister Eunice Mendizabal ordered police guarding government buildings not to carry firearms.

"No violence, no provoking violence, no giving in to provocation," Mendizabal said. "We must respect the people's right to protest."

A leading business, industrial and agricultural association added its voice to those calling for the president's resignation.

Pollo Campero, the country's iconic fried chicken chain, joined the stoppage and shuttered its outlets in Guatemala City on Thursday. Hamburger and pizza chains announced on their Facebook pages and websites that they were also joining the shutdown. The national chamber of commerce called on its members to let their employees attend the demonstrations "as long as they are peaceful and law-abiding."

On Wednesday, Perez Molina's former Vice President Roxana Baldetti was ordered to remain in jail pending trial on charges of conspiracy, customs fraud and bribery, based on allegations that she accepted $3.7 million in bribes from businessmen to evade import duties.

The scandal forced her from office earlier this year; she, too, has denied any wrongdoing.

And on Tuesday the Supreme Court ruled that Congress has the power to remove Perez Molina's immunity from prosecution as a sitting president.

Five of Perez Molina's 13 Cabinet ministers have resigned since Friday, as have eight vice-ministers, two secretaries and other government officials.