DENVER -- United Airlines announced Monday that the airline has made an additional $20 to $25 million over the past two months after it lowered business fares.

DIA's largest airline said that business travelers have responded favorably to the fare reductions.

"Our new business fares are great for customers and good for United's bottom line," said Doug Hacker, executive vice president-strategy. "Contrary to some reports in the media, the increase in business passenger volume has more than offset the lower fares."

The airline said it initiated the sharply reduced one-way business fares to draw in cost-conscious business travelers.

The new rules allow United customers to get up to 40 percent off unrestricted coach fares with no advance purchase. For customers able to buy tickets seven days in advance, the discount is even greater. There are no minimum or Saturday night stay requirements, though discounted tickets are not refundable, United said, but changes can be made for a $100 service fee. Customers can also stand by for free on earlier or later flights on the same day they are ticketed to fly.

United tested the new fare concept extensively on numerous Denver and Chicago routes.

The fares apply to travel in markets to and from Denver and Chicago -- the airline's top two hubs -- as well as more than 11,500 markets reached through connecting service.