CHICAGO – A transportation agency on Monday filed a lawsuit alleging that United Airlines is falsely claiming to buy huge amounts of jet fuel out of a small, rural Illinois office that doesn't even have a computer to avoid paying tens of millions of dollars in taxes in Chicago, where the purchases are allegedly being made.

The Regional Transportation Authority alleges United Aviation Fuels Corp., a subsidy of United Airlines, has operated a "sham" office in the DeKalb County community of Sycamore since 2001 after reaching an agreement to pay the town more than $300,000 a year — a fraction of what it would have owed in sales taxes in Chicago and Cook County.

"The only reason that United Fuels has an office in Sycamore is to attempt to create a sham tax situs (location) for fuel sales in a lower taxing jurisdiction," reads the lawsuit that the RTA said it filed Monday morning.