* Iran supply concern boosts prices * Obama says "no silver bullet" for high gasoline prices * Brent close to record high in euros (Adds details) By Alex Lawler LONDON, Feb 24 (Reuters) - Oil held above $123 a barrel on Friday and was heading for a fifth straight weekly gain, as concern over cuts in Iranian supply offset worries high oil prices could restrain demand. European buyers of Iranian oil have cut back on purchases ahead of a European Union embargo on imports of Iran's oil effective July 1. Some of Iran's biggest customers in Asia including China have also reduced purchases. Brent crude eased by 13 cents to $123.49 by 1100 GMT, after trading as high as $124.28 earlier. It reached $124.50 on Thursday, the highest intra-day price since May 3. "The supportive factors are on the supply side - Iran and Iran and Iran, with a bit of Syria and Sudan," said Christopher Bellew, a broker at Jefferies Bache in London. "It would not be at these numbers if it was not for the supply-side problems." U.S. crude was up 37 cents to $108.20, extending its rally into a seventh day, its longest rising streak since a 10-day gain in December 2009. Japan, the world's third-largest oil importer, may cut Iranian crude imports by a more-than-expected 20 percent as it seeks a waiver from U.S. sanctions. Last year, the country bought almost 9 percent of its crude from Iran. Iran said on Thursday it had maintained oil production levels despite sanctions, but analysts said they suspected Tehran was storing crude at sea while looking for new customers to evade Western measures. Brent's premium to U.S. crude CL-LCO1=R narrowed to $15.26 as inventories at Cushing, the delivery point for U.S. crude, fell last week. The spread had widened to over $20 earlier in the month on rising stocks in the U.S. Midwest. Supply concerns over Iran, as well as production losses in Syria and South Sudan, have offset concern about economic problems in Europe and a weaker global demand outlook. In euros, the price of Brent reached a record high on Thursday, adding rising fuel costs to the euro zone's debt troubles. The euro traded near 10-week high against the dollar and European shares edged up. Greece's second bailout since 2010 was sealed by euro zone finance ministers on Tuesday, averting the threat of a chaotic default next month but doing little to allay doubts about the country's long-term financial stability. Oil demand in Europe is falling and consumption in the United States - the world's top consumer - has hit the lowest level in nearly 15 years, a report from the Energy Information Administration showed this week. Even so, upbeat U.S. economic data on Thursday pointed to a more robust picture for demand. The number of Americans filing new claims for jobless benefits held at a four-year low, while December home prices rose 0.7 percent. President Barack Obama said on Thursday there was no "silver bullet" for high gasoline prices. Lawmakers from his own party are asking him to take steps to ease the price pressure in the short term. Democratic lawmakers on Wednesday urged the White House to signal it is ready to tap the country's strategic petroleum reserve. Obama made no mention of taking that step in his speech. (Additional reporting by Florence Tan in Singapore; editing by James Jukwey)

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