(Adds close of U.S. markets)
* S&P, Nasdaq hit record highs after Powell remarks
* Oil surges on China demand, signs that Iran supply curbed
* Dollar dips as Powell reaffirms Fed rate-hike policy
By Herbert Lash
NEW YORK, Aug 24 (Reuters) - Global equity markets rose on Friday after Federal Reserve Chairman Jerome Powell said the U.S. central bank's policies are best to keep the economy humming, spurring new highs on Wall Street, while oil surged on signs Iran sanctions may crimp worldwide supply.
The benchmark S&P 500 stock index notched its longest bull market, closing above its previous January high, after Powell's comments at a meeting of central bankers reaffirmed expectations of an interest rate hike in September and perhaps again in December.
The dollar weakened as Powell, speaking in Jackson Hole, Wyoming, said a gradual approach of raising rates remains appropriate to protect the U.S. economy and job growth, despite President Donald Trump's criticism of higher borrowing costs.
The dollar index fell 0.55 percent, while the euro and Japanese yen rose against the greenback. MSCI's gauge of stocks across the globe gained 0.53 percent while its emerging market index rose 0.19 percent.
Powell's remarks about inflation were seen by some as a sign that the Fed had little need to push rates above their perceived neutral rate, a level of equilibrium for economic growth.
Policymakers' latest assessment of the neutral rate was around 2.9 percent, or about 1 percentage point above the current level of between 1.75 and 2.00 percent.
The Fed is very confident in the U.S. economy and Powell indicated there is no intention of slowing down the Fed's rate hikes, said Chris Zaccarelli, chief investment officer at Independent Advisor Alliance in Charlotte, North Carolina.
"We are seeing some of the more cyclical sectors like energy, materials, continuing to move higher on the expectation that the Fed is going to let the economy run a little hot," Zaccarelli said.
The materials sector jumped 1.21 percent, the most among the 11 S&P sectors. The energy sector gained 0.80 percent.
In Europe, the pan-European FTSEurofirst 300 index of regional shares closed up 0.09 percent.
On Wall Street, the Dow Jones Industrial Average rose 133.37 points, or 0.52 percent, to 25,790.35. The S&P 500 gained 17.71 points, or 0.62 percent, to 2,874.69 and the Nasdaq Composite added 67.52 points, or 0.86 percent, to 7,945.98.
For the week, the S&P gained 0.87 percent, the Dow added 0.47 percent and the Nasdaq jumped 1.66 percent.
Strong economic growth and earnings and low interest rates have combined to continue to move the U.S. equity market higher, said Leo Grohowski, chief investment officer for BNY Mellon Wealth Management.
"The market's not cheap, but it's not as demandingly valued as many think it should be given that we continue to reach new highs," he said. "I'm very encouraged by the market’s ability to look through the disturbing political headlines of the week."
U.S. Treasury prices gave back earlier losses after Powell made the case for further rate increases.
Benchmark 10-year U.S. Treasury notes rose 2/32 in price to push yields down to 2.8152 percent. Before Powell's speech yields were at 2.850 percent.
Oil prices surged almost 2 percent on signs that sanctions on Iran may limit global supply and that a trade war may not curb China's appetite for U.S. crude.
Benchmark Brent crude oil settled up $1.09 a barrel at $75.82. U.S. crude gained 89 cents to settle at $68.72.
The euro rose 0.76 percent to $1.1625 and the Japanese yen strengthened 0.12 percent versus the greenback at 111.19 per dollar.
U.S. gold futures for December delivery settled up $19.30 at $1,213.30 per ounce.
Reporting by Herbert Lash in New York, additional reporting by Shreyashi Sanyal in Bengaluru Editing by Nick Zieminski and James Dalgleish