DHAKA, Bangladesh — Thousands of Bangladeshi garment workers staged angry protests on Monday, demanding justice after at least 112 people died over the weekend in a fire at a factory on the outskirts of Dhaka where labor advocates found the charred remains of clothing from brands sold at global retailers like Walmart.

The protests paralyzed much of the Ashulia area, an important industrial belt north of Dhaka, the capital, as workers blocked roads, prompting some factories to close for the day. A second garment factory in a different part of Dhaka was engulfed in flames on Monday morning. By afternoon, the second fire had been brought under control without any casualties being reported.

Prime Minister Sheikh Hasina offered prayers and sympathy for the families of the dead as her cabinet declared that Tuesday would be a day of national mourning. At the same time, she voiced suspicions that the fires were arsons intended to undermine the country’s garment industry. Without presenting any evidence of a broader conspiracy, she called for vigilance against sabotage.

The prime minister on Monday issued a call in Parliament to detain those who were “carrying out subversive activities” and to “take necessary actions against the culprits,” according to BSS, a state-owned news agency.

She said two workers were arrested over the weekend after attempting to set fire to another factory in the Dhaka area.

The weekend fire at the Tazreen Fashions factory ranks as one of Bangladesh’s worst industrial disasters. Witnesses described a desperate scene, as workers leapt from the upper floors of the factory, trying to land on nearby rooftops and escape the smoke and flames. Others suffocated inside the factory building, as the blaze apparently rendered stairwells impassable.

Kalpona Akter, a Bangladeshi labor leader, said she toured the factory after the fire was extinguished and found labels for a variety of global retailers, including Faded Glory, a brand she said was manufactured for Walmart. Ms. Akter said she also found labels for brands sold at leading European retailers.

“These international, Western brands have a lot of responsibility for these fire issues,” said Ms. Akter, the executive director of the Bangladesh Center for Worker Solidarity. “In this factory, there was a pile of fabrics and yarn stored on the ground floor that caught fire. Workers couldn’t evacuate through the stairs. What does this say about compliance?”

On Monday, Walmart said that the “Tazreen factory was no longer authorized to produce merchandise for Walmart,” but confirmed that one of its suppliers had “subcontracted” work to the factory without authorization. The company said that it was immediately terminating its relationship with the supplier.

A document posted on the Web site of Tazreen Fashions appeared to be an inspection complaint by Walmart. In the document, an “ethical sourcing” official flagged violations at the factory in May 2011, without detailing the problems.

The company that owns the factory indicated on its Web site that it had received a stamp of approval from an organization, Worldwide Responsible Accredited Production, that is enlisted by many Western retailers and manufacturers to certify that their suppliers are meeting certain standards. But in an interview, Avedis Seferian, the chief executive of the accreditation organization, said that claim was incorrect.

“This particular factory has never been WRAP-certified,” he said. “We’ve never been to that factory.”

Bangladesh is a garment powerhouse, with more than $18 billion a year in exports, ranking second behind China. More than three million workers are employed in the country’s 4,500 garment factories, most of them women. The industry has become an essential engine for the domestic economy, and a critical source of foreign currency that helps the government pay for imported oil.

But Bangladesh’s garment industry has also attracted rising international and domestic criticism over a poor fire safety record, low wages and policies that restrict labor organizing inside factories. The Clean Clothes Campaign, a European group that opposes sweatshops, said that more than 500 Bangladeshi laborers had died in factory fires since 2006. In 2010, 29 workers died from a fire inside a Bangladeshi factory making clothing for Tommy Hilfiger.

Garment factories across Bangladesh are expected to close on Tuesday for the day of mourning, as flags will be flown at half-staff around the country. Meanwhile, many family members of workers at the Tazreen factory are continuing to search for loved ones. Some victims were burned beyond recognition.

Nur Alam, 30, had been searching for his older brother, Anwar Hossain, since the fire erupted on Saturday. “I went inside the factory with some officials on Sunday,” Mr. Alam said. “I saw the remains of three people. It was impossible to identify them.”

The police were continuing to investigate the blaze. Delowar Hossain, the managing director of the parent group of Tazreen Fashions, could not be reached for comment on Monday.

The second fire broke out on Monday morning on a lower floor of a 12-story building that included three separate garment factories in the Uttara area of Dhaka. Muhammad Mahboob, a fire official, said an electrical spark in the building’s generator on a lower floor might have caused the fire. He said a dozen fire trucks reached the building quickly and doused the blaze within an hour, containing the damage to a single floor.

JULFIKAR ALI MANIK and JIM YARDLEY

Steven Greenhouse and Stephanie Clifford contributed reporting from New York.