Ford Motor Co said on Thursday its U.S. auto sales fell 5 percent in September from a year earlier as demand slumped off in part due to the end of the U.S. government's cash for clunkers incentive program.

Sales at Ford's core brands Ford, Lincoln and Mercury fell 6 percent.

Ford said U.S. sales for all of its brands fell to 114,655 vehicles in September, from 120,788 vehicles a year earlier, a decline of just over 5 percent.

Auto sales across the industry dropped in September compared with August, when the government's sales incentive program pushed the industry to its best sales results of 2009.

Ford said its retail sales through showrooms were down 14 percent in September from a year earlier while sales to fleet customers, including car rental agencies, were up 23 percent.

Sales at Ford's Volvo brand rose 16 percent to 4,716 vehicles in September. Ford has said it is in talks with interested parties to sell the Volvo brand.

The government's clunkers incentive program boosted U.S. sales from the last week of July through the first three weeks of August and auto industry analysts and executives expected a sharp pullback due to weaker demand and low inventories at dealerships.

Ford, the only large U.S. automaker not to reorganize through a government-supported bankruptcy this year, expects a gradual recovery in U.S. auto industry sales as the economy recovers and consumer confidence returns.

Ford expects U.S. auto industry sales for 2009 to come in at about 10.5 million vehicles to 11 million vehicles including medium and heavy duty trucks. It expects 2010 U.S. auto industry sales of about 12.5 million vehicles.

Ford shares were down 10 cents or 1.4 percent at $7.11 on the New York Stock Exchange in early afternoon on Thursday.

(Reporting by David Bailey, editing by Matthew Lewis)