(Reuters) - A group founded by a prominent anti-affirmative action activist on Monday sued Southwest Airlines ( LUV ), alleging that a two-decade-old program that awards free round-trip flights to Hispanic undergraduate and graduate students is racially discriminatory.

Edward Blum's American Alliance for Equal Rights in a lawsuit filed in federal court in Dallas alleged that the airline's program violated federal civil rights laws by excluding non-Hispanic students from eligibility for free tickets.

His group alleged that as a result, two Asian and white students who were members of his nonprofit were barred from applying to the program. The lawsuit seeks an injunction blocking Southwest ( LUV ) from using its eligibility criteria.

"Southwest Airlines ( LUV ) should immediately open this program to all students, regardless of their skin color or ethnic heritage," Blum said in a statement.

Dallas-based Southwest ( LUV ) did not immediately respond to a request for comment.

The lawsuit marked the latest in a series of cases Blum has filed in recent months challenging corporate diversity programs after another group he founded last year convinced the conservative-majority U.S. Supreme Court to bar the consideration of race as a factor in college admissions.

Monday's lawsuit centers on Southwest's ( LUV ) ¡Lánzate! Travel Award Program, which launched in 2004 and is operated in partnership with the Hispanic Association of Colleges and Universities.

To be eligible for four round-trip tickets, an undergraduate or graduate student must live at least 200 miles (322 km) from their home and be Hispanic. Southwest ( LUV ) says the program has helped more than 1,500 students.

The lawsuit alleged that the program violated Section 1981 of the Civil Rights Act of 1866, a Civil War-era law that bars racial bias in contracting.

It also claimed the program violated Title VI of the Civil Rights Act of 1964, which bars discrimination in federally funded programs or activities. Federal funding Southwest ( LUV ) received during the COVID-19 pandemic means the airline can be sued under that statute, according to the complaint.