(CNN) The Texas attorney general is investigating whether the city of San Antonio violated Chick-fil-A's religious liberty when it banned the fast food chain from its airport.
Last week, the San Antonio city council approved a new concessions contract for the San Antonio International Airport -- on the condition that Chick-fil-A be excluded.
Texas attorney general Ken Paxton slammed the city's decision as "discriminatory" and "inconsistent with the Constitution and Texas law." He echoed that thought in a tweet substituting waffle fries for the famous cannon in the Gonzales flag used during the Texas Revolution.
"The Constitution's protection of religious liberty is somehow even better than Chick-fil-A's chicken," Paxton wrote in a Thursday letter to the San Antonio mayor and city council. "Unfortunately, I have serious concerns that both are under assault at the San Antonio airport."
CNN has reached out to the office of San Antonio Mayor Ron Nirenberg for a response.
Councilman Roberto Treviño, who made the motion to exclude Chick-fil-A, said San Antonio does not tolerate "anti-LGBTQ behavior."
"With this decision, the City Council reaffirmed the work our city has done to become a champion of equality and inclusion. San Antonio is a city full of compassion, and we do not have room in our public facilities for a business with a legacy of anti-LGBTQ behavior," Treviño said in a March 21 statement. "Everyone has a place here, and everyone should feel welcome when they walk through our airport."
In a response to CNN on Friday, Treviño said, "I'm confident that we have followed all our rights and laws as given to us as a City Council, and we did everything by the book.”
In a separate letter Thursday, Paxton also requested that the US Department of Transportation open an investigation into whether San Antonio's decision to ban Chick-fil-A from its airport violated federal law. The Transportation Department did not immediately return CNN's request for comment.
CNN has also reached out to Chick-fil-A for comment.
Chick-fil-A has come under fire from supporters of same-sex marriage in recent years after its president, Dan Cathy, said the company supported "the biblical definition of the family unit."
ThinkProgress, a left-leaning website, reported last week that Chick-fil-A donated $1.8 million in 2017 to groups with a discriminatory record against the LGBTQ community. The company responded, saying in a statement that "to suggest that our efforts in supporting these organizations was focused on suppressing a group of people is misleading and inaccurate."
Nirenberg, who's up for reelection, defended his vote supporting the motion during a mayoral debate last week.
"There are many people in the community that are uncomfortable with Chick-fil-A," Nirenberg said. "And I would ask you, have you ever tried to buy waffle fries on a Sunday? They're closed. Fifteen percent of sales generated in the airport come on a Sunday.