LITTLE ROCK, Ark. – Federal agents raided Wal-Mart’s headquarters and 60 of its stores across the country Thursday, arresting more than 300 illegal workers in an immigration crackdown at the world’s biggest retailer.

The workers were members of cleaning crews hired by outside contractors, but federal law enforcement officials who spoke on the condition of anonymity said Wal-Mart had direct knowledge of the immigration violations. They cited recordings of meetings and conversations among Wal-Mart executives, managers and contractors.

“We have seen no evidence of this from the INS, and, if that turns out to be true, we will cooperate fully with law enforcement officials,” Wal-Mart spokeswoman Mona Williams said.

The workers were arrested as they finished their night shifts at Wal-Mart stores in 21 states. Agents also hauled away several boxes of documents from an executive’s office at Wal-Mart headquarters in Bentonville.

An employer can face civil and criminal penalties for knowingly hiring illegal immigrants or failing to comply with certain employee recordkeeping regulations.

It is not known whether the INS will raid any more Wal-Mart stores throughout the country or even in Maine, said the company’s east region spokeswoman, Mia Masten, on Thursday afternoon.

“I’ll tell you, I hope not,” she said.

An undisclosed number of Wal-Mart stores located in Maine use outside contractors to perform cleaning services, Masten said. However, she said she did not know whether the contractors in Maine are part of the same company as those targeted in other states or whether the contractors in Maine employ migrant workers.

In New England, the INS raided seven stores in Connecticut, Massachusetts and New Hampshire on Thursday morning.

“We’re trying to understand the fullness of the scope,” Masten said. “Right now, honestly, we’re trying to get our hands around this. We don’t know if the INS investigation involves one or more than one contractor.”

The state Department of Labor’s Division of Migrant and Immigrant Services is not aware of whether the cleaning services Wal-Mart uses in Maine are employing documented migrant workers, according to director Vaughn LeBlanc.

He said if the cleaning service is an out-of-state company, “they wouldn’t have to notify me because the workers are not being paid by a company based in the state of Maine.”

Wal-Mart Stores had sales last year of $244.5 billion. The company has about 1.1 million employees in the United States, and it uses more than 100 third-party contractors to clean more than 700 stores nationwide, Williams said.

“We require each of these contractors to use only legal workers,” she said.

The law enforcement sources said the investigation grew out of earlier probes of Wal-Mart cleaning crew contractors in 1998 and 2001.

All the arrested workers were in the country illegally, said Garrison Courtney, a spokesman with Immigration and Customs Enforcement. They were detained at local immigration offices. Those who had no criminal record were released with instructions to appear before immigration judges.

Wal-Mart is not the first big company to be targeted in an immigration investigation. Six managers at Tyson Foods, based one town away from Wal-Mart in Springdale, were charged in an immigrant-smuggling case in 2001.