Auto makers used the highest level of incentives in 25 years in an effort to revive flagging sales in the U.S., according to a report published Tuesday.

Chrysler LLC made the most aggressive move last month, according to data compiled by auto sales tracker Edmunds.com, while Japanese manufacturers scale back discounts and offers compared with a year earlier.

Average incentives in the U.S. climbed 15.9% year-on-year in February to reach 20% of sticker price and were 8% higher than in January.

The report comes ahead of February auto sales data due later Tuesday, with manufacturers indicating another fall to an annualized level of 9 million to 9.5 million vehicles.

Chrysler on average spent $5,566 on each car and truck it sold in February, a record level according to Edmunds. That's an increase of 30% from January and a nearly 60% jump from a year earlier, when Chrysler's average incentive was $3,520.

Jim Press, Chrysler's president, said Tuesday that the auto maker gained U.S. retail share last month.

Detroit's auto makers in recent years have tried to scale back profit-eroding discounts but have been forced to return to the practice as U.S. sales stay at multi-decade lows.

General Motors Corp. (GM) and Chrysler are scrambling to stabilize their operations as they seek $21.6 billion in emergency federal loans on top of the $17.4 billion the auto makers already received.

-By Sharon Terlep, Dow Jones Newswires; 248-204-5532; sharon.terlep@dowjones.com.

(John Stoll contributed to this article.)