US auto sales fell precipitously in the first part of October, as employee-discount incentives ended and petrol prices made consumers jittery, the results of a survey suggested.

The numbers also showed a possible fallout from strong summer sales, according to Power Information Network, a division of JD Power and Associates, whose report was cited by the Associated Press (AP).

AP said the survey found new vehicle sales were down 33% in the first nine days compared with the same period a year ago, and down 44% compared with the first nine days of September.

General Motors sales were down 57% compared with early October 2004, while Ford sales were off 45%. The other seven major automakers also showed declines, AP said.

"The aftermath of the employee pricing programs is having a dramatic impact," Jeff Schuster, executive director of global forecasting at JD Power, told the news agency. "A lot could happen between now and the end of the month, but at this point, we're on track for an October like we haven't seen since the early 1990s."

GM spokeswoman Susan Garontakos reportedly said the company wasn't planning any immediate changes to its incentives, but saw the October decline as attributable mostly to 2005 model year vehicles being cleared out earlier in the year.

George Pipas, Ford's US sales analysis manager, declined to comment to the Associated Press on the report, but noted that the automaker had said when reporting September sales that it expected October to be a weak sales month.

According to the PIN survey, DaimlerChrysler sales were off 32% in early October, while Nissan North America recorded a 21% decline. American Honda Motor Co. showed the smallest decline of 8%, followed by Toyota Motor Sales USA, which had a 14% drop, the Associated Press added.

"It will be interesting to see if the automakers, particularly GM and Ford, can hold back on incentives if their sales and share continue to slip," Tom Libby, senior director of industry analysis at PIN, told the news agency. "I expect they will find a way to boost sales. I doubt that they will just sit back and let this trend continue."