By Bernie Woodall and Joseph White

DETROIT (Reuters) - Ford Motor Co <F.N> on Thursday declared the U.S. auto industry's long recovery is at an end, sending its stock and those of rival auto companies tumbling.

"The growth is over," Ford Chief Financial Officer Robert Shanks told Reuters in an interview. Shanks earlier forecast U.S. light vehicle sales would fall in 2016 from the record of 17.47 million last year, and fall again in 2017.

Pent-up demand built during the last recession has been satisfied, and lower used car prices are drawing some buyers away from new vehicles, he said, adding however, "We’re not talking about a collapse."

Ford's warning put at center stage a debate that has been running for months in Detroit about how much further the long bull market in U.S. vehicle sales has to run.

The debate has consequences. Based on its forecasts, Ford said it will accelerate cost cutting and cut North American production in the second half of the year. That could affect workers' paychecks, payments to suppliers and service vendors, and investment plans.

Ford shares skidded 8.2 percent on Thursday. General Motors Co <GM.N> stock fell 3.2 percent and Fiat Chrysler Automobiles NV <FCAU.N> shares closed down nearly 4.8 percent.

Mike Jackson, the head of AutoNation Inc <AN.N>, the largest U.S. auto dealership chain, has warned for much of the year that U.S. vehicle demand is hitting a plateau, and has called on automakers to rein in production to avoid overstocking vehicles, particularly small cars. AutoNation reports second quarter results Friday.

GM and Fiat Chrysler, however, are taking more positive stands, forecasting continued strength in U.S. and North American vehicle demand.

GM last week raised its outlook for full-year results and reported stronger margins in its North American operations. Chief Executive Mary Barra told analysts last week average prices for GM vehicles were up $1,500 in the second quarter from a year ago. She predicted "continued momentum" in the second half as the company launches new models and increases production of trucks and sport utility vehicles.

Fiat Chrysler said earlier this week it expects North American demand to "remain strong" and Chief Executive Sergio Marchionne predicted "positive pricing going forward" in the market.

However, Marchionne warned that unless the company can negotiate more competitive labor deals with the United Auto Workers, it will stop building sedans and compact cars in the United States. The slump in Fiat Chrysler's sedan sales reflects a broader shift - no longer is consumer demand strong across all market segments and body styles.

The call on the North American vehicle market matters to investors because U.S. sales of light trucks and SUVs generate the bulk of global profits for GM, Fiat Chrysler and Ford.

Ford said it expects the U.S. economy to grow 1.9 percent to 2.3 percent this year, lower than Ford's previous expectation of 2.1 percent to 2.6 percent growth.

The Federal Reserve last month trimmed its forecast for U.S. economic growth to 2 percent from 2.2 percent in March.

SIGNS OF STRESS

Ford on Thursday reported weaker-than-expected profit in the second quarter, and its results showed signs of stress in various ways. In North America, revenue grew 2 percent to $23.8 billion for the quarter.

But discounts took $999 million more out of the latest quarter's pretax profit than in the second quarter a year ago, and pretax profit in the region fell by 5 percent to $2.7 billion.

"The competitive environment has increased as demand has slowed," Chief Executive Mark Fields said during a conference call with investors. "This has resulted in higher industry incentives ... as various competitors protect their share."

Ford’s operating automotive margin in North America was 11.3 percent during the quarter, down from 12.2 percent a year earlier. Shanks said Ford believed it could sustain North American margins in an 8 to 10 percent range from peak sales to trough.

Analysts said some of Ford's problems appeared related to product and competitive issues, rather than macro-economic factors.

“GM said recently that it will have more truck production in the second half of the year to meet some demand that they’ve been leaving on the table,” said David Whiston, autos analyst with Morningstar. Meanwhile, Ford will be taking on heavy costs to roll out a new line of Super Duty trucks.

Also, Shanks said a weaker British pound following the June 23 vote by Britain to leave the European Union, known as "Brexit," cost the company about $60 million in the second quarter.

The 2016 impact of Brexit on Ford is expected to be $200 million, he said, and each year until Britain leaves the EU will cost the company $400 million to $500 million, Shanks said.

Ford said its costs also rose for safety recalls, which are counted as part of its net income. The expense to cover recalls relating to air bag inflators made by Takata Corp <7312.T> was about $100 million in the quarter, Shanks said.

(Editing by Bernadette Baum and Chris Reese)