CHICAGO — Nearly two dozen illegal immigrants were arrested yesterday, accused of using fake security badges to work in critical areas of O’Hare International Airport, including the tarmac, authorities said.

The 23 illegal workers were employed by Ideal Staffing Solutions Inc., whose corporate secretary and office manager also were arrested after an eight-month investigation that involved federal, state, and Chicago authorities.

The company contracted work for carriers including United Airlines, KLM, and Qantas, a U.S. Immigration and Customs Enforcement agent, Elissa Brown, said.

“The investigation identifies a vulnerability that could compromise national security, while bringing criminal charges against individuals who built an illegal work force into their business practice,” Ms. Brown said.

Ideal Staffing officials did not return a telephone message left after business hours yesterday by the Associated Press.

Much of the investigation centered on the airport security badges issued by the Department of Aviation, a U.S. attorney, Patrick Fitzgerald, said. Agents found that 110 of the 134 badges issued to Ideal Staffing workers did not match the individuals who carried them, he said. The discrepancies were first noted in March by a U.S. Customs and Border Protection inspector, Mr. Fitzgerald said.

“If we are to ensure public safety, we must know who has access to the secure areas of airports,” Mr. Fitzgerald said. “A fundamental component of airport safety is preventing the use of false identification badges, and punishing those who commit or enable such violations.”

Mary Gurin, 36, of Carpentersville, and Norinye Benitez, 24, of Franklin Park, were each charged with one federal count of harboring illegal immigrants for gain and one federal count of misuse of Social Security numbers. They were scheduled for a preliminary appearance later yesterday in U.S. District Court, Ms. Brown said.

Ms. Benitez is believed to be an illegal immigrant from Mexico, and Ms. Gurin employed her and signed her airport badge application while knowing her illegal status, Ms. Brown said.

The workers arrested, 21 from Mexico and two from Guatemala, were being held in the Cook County jail.