General Motors Corp. is raising incentives to boost sales in August, mainly for full-size pickup trucks, the automaker's global head of product development said on Thursday.

We are boosting incentives in August, Bob Lutz said on the sidelines of an industry conference in Traverse City, Michigan. I think it's predominantly in the full-size pickups, he added.

Lutz said the automaker increased incentives this month to compete with rivals offering big discounts, after July sales were weaker than we would have wanted it to be.

GM is boosting incentives even as it has been trying to stick to a strategy of lower incentives and clearer pricing after decades of big discounting programs that eroded profits.

GM's U.S. sales fell nearly 19 percent in July, hurt by weakness in the housing market, higher gas prices and tough competition.

GM's chief sales analyst, Paul Ballew, last week said the automaker would be more aggressive on incentive spending over the remainder of the year, in response to heavy discounts from competitors, especially on pickup trucks.

We're going to be very responsible with what we do and get the right balance between selling at a profit versus really watching share decline, Lutz said on Thursday.

The market for pickup trucks, which accounts for nearly 13 percent of overall U.S. sales, has become the most fiercely competitive segment as automakers sacrifice margins with expensive sales offers in order to protect market share.