A major overhaul of concessions coming soon at the Atlanta airport has sparked a dispute between the city and a labor union concerned about workers losing their jobs in the shuffle.

The union that represents workers at HMSHost, one of the largest concessionaires at Hartsfield-Jackson International, wants assurances workers can hold onto jobs at the airport. It also wants a requirement that all concessionaires strike preliminary agreements with unions that could pave the way for representation.

The city of Atlanta at first went forward with such language last week, but a day later rescinded it. Mayor Kasim Reed's deputy chief of staff, Katrina Taylor Parks, said it was an error.

"There was definitely a mix-up," Parks said. Instead, the city issued language saying that "encouraging retention of high performing airport concessions workers" is essential to its mission, the first time it has added such wording, she said. The city also plans to add incumbent concessions workers to its First Source Jobs program list of job seekers from which large city contractors are required to hire a portion of their workers.

The union, Unite Here, opposed the change, saying the new language contains no mandates to retain workers.

About 1,500 who work for concessions at the airport are "wondering what's going to happen with their jobs once this change happens," said Charlie Flemming, president of the Atlanta-North Georgia Labor Council, at a city council transportation committee meeting Wednesday.

The airport is awarding concessions contracts for space in the new international terminal and also much of the space in the existing terminal and concourses.

Parks said the city supports the concept of keeping workers in their jobs as the new concessions contracts are awarded, but added: "We are not at a point to go on record and mandate" it.

Bhav Tibrewal, senior research analyst for the union's airport group, said the union "will continue to push the city" for the labor retention language. But the city said it is through with addenda on the concessions.

The requirements could have posed issues for companies that don't have unions and would be required to strike preliminary agreements.