UPDATE 1-Flights halted at Chicago airports due to smoke at radar center

(Adds fire extinguished, possible cause, flight delays)

CHICAGO, May 13 (Reuters) - A fire at a Federal Aviation Administration flight approach control center in Illinois that halted air traffic into and out of Chicago's two airports on Tuesday has been put out, but the halt remained in effect and flights were delayed across the country, officials said.

Traffic was halted near midday at O'Hare International Airport and Midway Airport after workers were forced to clear the control center in the Chicago suburb of Elgin due to smoke in the building, an FAA spokesman said.

The stop was still in effect as of about 2 p.m. Central Time (1900 GMT), according to Chicago Department of Aviation spokeswoman Karen Pride.

The fire was put out at about 1:30 p.m. CT and appeared to have been caused by an electrical malfunction in a bathroom exhaust fan, said Elgin Fire Captain Anthony Bialek. He said it caused "very minor damage" but a lot of smoke.

"It doesn't look criminal or anything like that," Bialek said, adding that workers were being let back into the building.

Local television showed long lines of jets backed up at O'Hare and long lines of passengers re-booking flights.

"It's comparable to a snow-storm type event ...," DePaul University transportation expert Joseph Schwieterman said. "The rest of the country is feeling the pain right now."

Operations were transferred immediately to the Chicago en route control center in Aurora, Illinois, according to an FAA spokesman.

The evacuation of the Chicago Terminal Radar Approach Control facility, or TRACON, occurred at about 11:30 a.m. Central Time.

(Reporting by Mary Wisniewski in Chicago and David Bailey in Minneapolis; Editing by Marguerita Choy and Dan Grebler)