NEW YORK — United States Steel Corp.'s quarterly profit more than tripled as higher prices led to record gains in its tubular and flat-rolled steel businesses, but the company warned Tuesday that softening demand in North America and Europe will hurt results for the rest of the year.

U.S. Steel Chief Executive John Surma said the Pittsburgh-based company turned in the most profitable quarter in its history, but warned that fourth-quarter results will decline due to "the volatile global economic climate."

He cited "softening demand and prices for flat-rolled products in North America and Europe." He also said it is hard to gauge near-term prospects because of a low number of backorders.

Flat-rolled steel is a sheetlike item used to make auto exteriors and appliances.

The company's production was reduced late in the third quarter to match declining order rates for its flat-rolled and European segments. Some of the largest declines in orders for flat-rolled steel have come from the struggling U.S. auto industry and appliance makers like Whirlpool, which said Tuesday it is eliminating about 5,000 jobs this year and next as it responds to the long downturn in the U.S. housing market.

Steel prices globally have deteriorated in recent weeks as demand has slowed along with the worldwide economy.

U.S. Steel reported net income of $919 million, or $7.79 per share, in the third quarter, compared with $269 million, or $2.27 per share, a year earlier.

Excluding one-time charges, U.S. Steel earned $8.79 per share and quarterly sales soared 68 percent to $7.31 billion, easily beating Wall Street forecasts.