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The Illinois attorney general is investigating a bus company after complaints that the company sent an email advertisement last weekend that some said insulted Asians and Asian Americans.

Illinois Attorney General Lisa Madigan issued a subpoena to Suburban Express Monday, seeking "documents, records and information that will help determine whether the company's policies and practices" violate state law, according to a statement from the attorney general's office.

The subpoena came after the office received multiple reports of an email that "allegedly indicated that the company discriminates on the basis of race and national origin," according to the statement. The University of Illinois at Urbana-Campaign criticized the email, calling it “racist and bigoted” in a Dec. 3 statement.

Statement in Response to Suburban Express Ad from Vice Chancellor Young, @ISSSIllinois, and @Illinois_Intl. Full statement: https://t.co/fnhWcJJKY1 pic.twitter.com/oJqxLZJqun — UI Student Affairs (@ILStuAffairs) December 3, 2017

Images of the email provided by the university show that Suburban Express — a private company whose routes include stops near campus and in the Chicago area — highlighted 11 aspects of its service, including that passengers “won’t feel like you’re in China when you’re on our busses.”

“I am concerned that this advertisement may reflect that Suburban Express is discriminating against potential customers,” Madigan said in the statement. “Under the law, access to transportation must not be impacted or based on a person’s race or national origin.”

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Suburban Express could not be reached for comment.

In a statement posted Sunday evening, then deleted and republished on Monday, on the company’s Facebook page, Suburban Express wrote that a recent email “mentioned that Suburban Express riders would not encounter Chinese exchange students,” because those students ride a competitor. The company acknowledged that it was an “ill-advised statement.”

“We apologize for our insensitive statement, and we hope to do a better job of unifying the campus community in the future, from our office in the heart of campustown,” the statement read in part.

In an additional statement posted Tuesday night, Illinois time, the company acknowledged the attorney general's investigation, saying it was working to cooperate.

The University of Illinois at Urbana-Champaign has had deep ties with China dating back more than a hundred years, according to Robin Kaler, associate chancellor for public affairs. The school maintains a Shanghai office and, according to the university, one-third of all Chinese students who came to the U.S. between 1910 and 1950 attended the Urbana campus.

Currently, about 11,000 of the school’s approximately 45,000 graduates and undergraduates are international students, according to Kaler, with about 6,000 coming from China.

“It was terrible,” Kaler said Monday. “This is as far from the core values of the university as you can possibly get.”

The university is not the only group criticizing the company. Alderman Ameya Pawar, who represents Chicago's 47th Ward and sits on the city council's Committee on Aviation, called on Monday for Suburban Express to appear before the council after he said he saw reports about the email and received complaints from Chinese community leaders.

Dear Suburban Express: This is not an apology. This is an unbelievably offensive and bigoted response. Shame on you. Since you serve O'Hare International Airport, I am going to call for a hearing on your business practices. In them meantime, you may want to issue a real apology. pic.twitter.com/kNFkM1e0BW — Ameya Pawar (@Ameya_Pawar_IL) December 4, 2017

"As an elected official, I recognize that free speech is protected under the U.S. Constitution, and you have a right to be a bigot," Pawar said, adding that he had also heard allegations that consumers were being mistreated and the ad was not an isolated incident.

"In that context, and the city council having a regulatory function, I think it's worth having a conversation, giving them hopefully, a forum to apologize to the city, and the University of Illinois, and to the Chinese and Chinese-American community," he added.

"Suburban Express has reached out to Alderman Ameya Pawar," Suburban Express wrote on Facebook Monday afternoon. "We screwed up and we know it. Our apology was inadequate. We hope to open a dialogue with Alderman Pawar about our shortcomings and how to make our services more inclusive in the future."

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