SPRINGFIELD – A planned coal gasification plant for Chicago’s south side will increase natural gas prices for Ameren and Nicor customers downstate, a coalition of business and environmental groups said Thursday.

They are asking Gov. Pat Quinn to veto a bill passed in the closing hours of the spring session that would allow the $3 billion facility to be built by Leucadia National Corp.

The Leucadia plant would convert coal to synthetic natural gas that then would be sold to Illinois utilities. The opponents argue that the plant does not make economic sense for consumers when the price of natural gas recovered from the ground is at an all-time low.