(Updates with start of limited arrivals, departures; delay information)
By Mary Wisniewski
CHICAGO, May 13 (Reuters) - Smoke at an Illinois flight control center halted air traffic at Chicago airports for about three hours on Tuesday and forced hundreds of flights to be canceled, officials said.
Traffic was halted at O'Hare International Airport and Midway Airport after workers were forced to clear the Federal Aviation Administration flight approach control center in the Chicago suburb of Elgin at 11:30 a.m. CDT (1630 GMT), an Federal Aviation Administration spokesman said.
The smoke was caused by a faulty motor in the heating, ventilation and air conditioning system, but there was no fire, an FAA spokesman said.
The FAA is working to clear residual smoke from the radar room to let air traffic controllers return to work.
About 700 flights were canceled at Chicago airports, and limited arrivals and departures resumed more than three hours after the incident.
At O'Hare, most flights in and out of the airport were delayed by more than an hour, according to the city's department of aviation.
Local television showed long lines of jets backed up at O'Hare and queues of passengers re-booking flights. Major Chicago carriers include United Air Lines Inc, American Airlines Inc and Southwest Airlines Co .
""The rest of the country is feeling the pain right now," DePaul University transportation expert Joseph Schwieterman said.
Operations were transferred to the Chicago en route control center in Aurora, Illinois, according to the FAA. (Reporting by Mary Wisniewski in Chicago and David Bailey in Minneapolis; Editing by Marguerita Choy and Dan Grebler)