A Midwest charter school operator linked to a high-profile Islamic cleric is using a controversial visa program to import foreign-born teachers into districts where there are already high unemployment rates among American-born educators. Critics say the situation is further evidence of the need for comprehensive immigration reform.

Des Plaines, Illinois-based Concept Schools is operated by followers of Fethulla Gulen, a Turkish preacher and former Imam who backs a form of Islam known as Hanafi. The system rejects some of the more fundamentalist interpretations of the Koran, but some U.S. Hanafi members were behind an infamous hostage-taking incident in Washington, D.C., in 1997 that led to the shooting of then-D.C. councilman and former Mayor Marion Barry.

Gulen is also a longtime critic of Recep Tayyip Erdogan. He slammed the Turkish president this week for failing to confront Islamic State fighters amassed on the country’s border with Syria and for cracking down on protesters who support Kurds who are waging a campaign against IS.

Concept Schools is privately held but receives public funds from states where it operates. It maintains more than 30 K-12 institutions throughout Illinois and Ohio. Over the past several years it has imported more than 400 teachers from Turkey on H-1B visas, according to data cited Wednesday by the Cincinnati Enquirer.

The H-1B visa is supposed to be reserved for immigrants who work in a “specialty occupation,” which United States Citizenship and Immigration Services defines as a job that is “specialized and complex.” The H-1B visa is most frequently awarded to individuals with advanced skills in math, science and information technology. A total of 85,000 are available to new applicants each year. India-based IT outsourcers Infosys, Tata and Cognizant were the top three users of the H-1B program last year, according to an analysis by Computerworld.

Critics say the program is rife with abuse. The Enquirer quoted one former Concept employee who said he obtained H-1B approval as an IT administrator but was later shifted to a teaching position, despite his poor English skills. “I couldn’t even understand when the kids wanted a Kleenex or tell them to stop chewing gum,” Mustafa Emanet, who was hired in 2006, told the newspaper.

At the same time, “There are a lot of qualified teachers that have gone through education and licensing in Ohio that are not being hired,” Brian Rothenberg, executive director of the advocacy group ProgressOhio, told International Business Times. “They have been able to take advantage of lax oversight of public dollars and use the program to bring teachers into a state that quite frankly has a lot of unemployed teachers,” Rothenberg said.

Ron Hira, a professor at Howard University in Washington, D.C., who has long studied the H-1B, told IBTimes in an email that “it is extremely easy for an employer to avoid hiring qualified American workers” under the program.

Backers of the visa, including former Microsoft Chairman Bill Gates and former New York City Mayor Michael Bloomberg, have said it should be expanded due to what they say is a lack of skilled technical workers in the U.S.

The controversy is sure to renew calls to revamp the H-1B program as part of broader immigration reform. A bipartisan immigration bill that died in Congress last year would have increased the number of available H-1B visas to 180,000, but it also would have imposed stricter enforcement mechanisms to prevent misuse.

Neither the White House nor Congress is expected to revisit immigration reform until after the November midterm elections. President Obama has floated the idea of using executive authority to address some immigration issues, but has not spoken directly to the H-1B program.

Representatives for Concept Schools did not respond to a request for comment.