UPDATE 2-Mexico's Cemex quarterly net profit falls 7 pct

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MONTERREY, Mexico, Oct 25 (Reuters) - Mexico's Cemex, the world's top building materials company by revenue, posted a 7 percent fall in third-quarter net profit to $780 million on Thursday, slightly above analysts' expectations.

The slide in profit was due to an extraordinary $100 million gain from an asset sale in the third quarter of 2006 and extra costs generated by Cemex's July 2007 purchase of Australia's Rinker.

Cemex (CX.N)(CMXCPO.MX) said its July-to-September revenues rose 31 percent to $6.1 billion. Earnings before interest, taxes, depreciation and amortization (EBITDA) rose 23 percent to $1.4 billion, the company said.

A Reuters survey of six analysts forecast, on average, that Cemex's quarterly net profit would be $750 million.

Cemex's sales in the United States, its top market, rose 57 percent in the quarter to $1.7 billion and EBITDA rose 25 percent to $420 million as the Monterrey-based company integrated Rinker into its results for the first time.

The results reflect Rinker's strong presence in the United States, which is experiencing a crisis in its subprime mortgage sector that caters to borrowers with poor credit histories. That is bad news for a sector also suffering from an inventory build-up and an increasing number of borrowers falling behind with mortgage payments.

As a result, Cemex's U.S. cement volume fell 1 percent in the quarter. "Building materials dynamics in the U.S. continued to be driven by the ongoing downturn in the residential sector," the company said in a statement.

Cemex, which operates in more than 50 countries, paid $15.3 billion for Rinker. Cemex said its net debt at the end of the third quarter was $19.2 billion, an increase of some $15.1 billion during the quarter, due to the Rinker acquisition.

"We remain focused on paying down debt," said Hector Medina, Cemex's planning and finance chief.

Cemex's other operations reported strong results. Net sales in Spain rose 16 percent to $502 million and increased 10 percent to $550 million in the United Kingdom. Net sales rose 28 percent in South and Central America and the Caribbean.

Net sales in Asia and Australia surged 515 percent to $509 million versus the third quarter of 2006 and EBITDA rose 369 percent mainly due to the integration of Rinker operations. (Reporting by Robin Emmott)