US STOCKS-Wall St at 13-month highs as dollar slips

* S&P energy sector up 2.5 percent as oil rallies

* Fed chairman downbeat on economy, says watching dollar

* Major stock indexes gain more than 1 percent

* For up-to-the-minute market news, click [STXNEWS/US]

(Updates to early afternoon)

By Rodrigo Campos

NEW YORK, Nov 16 (Reuters) - U.S. stocks rose on Monday to 13-month highs led by energy and materials shares even as Federal Reserve Chairman Ben Bernanke said the economic expansion probably will not be as robust as hoped.

Commodity-related companies led the broad advance as oil and metals prices rose, lifted by a declining U.S. dollar. The dollar weakness prompted investors into riskier assets like commodities and stocks.

Shares of AK Steel Holding Corp (AKS.N) jumped 7.5 percent to $18.69, while Exxon Mobil Corp (XOM.N) added 2.9 percent to $74.55 and led the Dow industrials. Both the S&P energy .GSPE and the materials sectors .GSPM rose more than 2 percent.

The greenback retreated as the United States and China failed to reach an agreement over currencies at a summit of the Asia Pacific Economic Cooperation forum in Singapore, and was further pressured by better-than-expected U.S. retail sales data. For details, see [ID:nAPEC] and [ID:nN16500414]

Bernanke commented on the dollar's decline, rare for an official of the Fed, which usually leaves dollar policy to the Treasury. He said the Fed is attentive to changes in the U.S. currency and the Fed's mandate will help ensure the greenback remains strong. [ID:nN16493345]. The dollar briefly strengthened after Bernanke's comments, knocking stocks temporarily lower.

But traders believe that the Fed chairman is limited in his ability to affect the currency's value while still using policy to lift the economy from recession.

"(Bernanke) is talking out of both sides of his mouth," said Joe Saluzzi, co-manager of trading at Themis Trading in Chatham, New Jersey.

"If you take away stimulus, this economy falls apart. He knows it. He's boxed in here, he can't raise rates. It's impossible. So what do we do? We continue to buy equities because that's what the trade is."

The Dow Jones industrial average .DJI gained 137.25 points, or 1.34 percent, to 10,407.72. The Standard & Poor's 500 Index .SPX rose 17.40 points, or 1.59 percent, to 1,110.88. The Nasdaq Composite Index .IXIC added 31.71 points, or 1.46 percent, to 2,199.59.

Crude futures CLc1 jumped 3.3 percent to $78.89 per barrel, while the dollar index .DXY fell 0.5 percent and was slightly above a 15-month low set last week.

Freeport-McMoRan Copper & Gold Inc (FCX.N) shares jumped 3.8 percent to $84.63, as December gold futures GCZ9 touched a fresh high above $1,134 an ounce. (Additional reporting by Ellis Mnyandu; Editing by Kenneth Barry)