NASHVILLE, Tenn. (AP) _ The U.S. Justice Department wants to know more about a proposed $585 million merger that would nearly double the size of the nation's largest parking lot operator.

Nashville-based Central Parking Corp., the nation's No. 1 provider of parking services, announced plans in September to acquire No. 2 Allright of for $355 million in stock and assumed debt of $230 million.

On Tuesday, the companies released a statement saying the Justice Department's antitrust division had requested more information about the deal.

Merger experts say the request could signal trouble, but company officials expect to complete the deal by January, as scheduled.

The concerns are most likely that the companies control so many parking lots in some cities that it would create a monopoly in those areas if they merge.

Central Parking chief financial officer Stephen Tisdell said the problem simply may be the lack of available information about the fragmented parking industry.

Central Parking operates more than 2,400 parking facilities in 35 states, the District of Columbia and nine other countries. Allright operates more than 2,300 facilities in 33 states, D.C. and Canada.