Aquila Inc. said Tuesday that its fourth-quarter loss deepened due to impairment charges for two Illinois power plants the company is selling.

But the Kansas City, Mo.-based company said it had cut its annual loss by 21 percent on stronger utility business and the sale of electric and natural gas assets in four states.

For the three months ending Dec. 31, Aquila reported a loss of $127.8 million, or 34 cents per share, on revenue of $397.7 million. During the same period a year ago, the company reported a loss of $81 million, or 21 cents per share, on revenues of $272 million.

Aquila’s natural gas business for Kansas is based in Lawrence.