The International Monetary Fund (IMF) has revised up British economic growth from 0.6 percent to 0.9 percent this year in its World Economic Outlook Update report, released on Tuesday in Washington. Though trimming down the world output by 0.2 percent to 3.1 percent and 3.8 percent respectively in 2013 and 2014, IMF turns to be more optimistic on the British economic outlook than it was in April. It expects the 2.43-trillion-US dollar economy to grow at 1.5 percent next year, which would be higher than the 0.9 percent growth in Euro Area. But IMF warned that in advanced economies, longer-term interest rate and financial market volatility have risen. Peripheral euro area sovereign spreads have widened again after a period of sustained declines. The IMF pointed out emerging market economies have generally been hit hardest, as recent increases in advanced economy interest rates and asset price volatility, combined with weaker domestic activity, have led to some capital outflows, equity price declines, rising local yields, and currency depreciation. The National Institute of Economic and Social Research said on Tuesday that Britain\'s economic growth rate would double to 0.6 percent in the second quarter, largely driven by the private service sector. That reflects the more pleasant chorus on the country\'s output from the think tanks. The Organization for Economic Cooperation and Development (OECD) said yesterday that the British economy is on course for above trend growth, with its Composite Leading Indicators (CLIs) stabilized at 100.7 (above 100.1 shows growth) in May.