The Organisation for Economic Co-operation and Development predicted an annualised GDP growth rate of 3.3% in both the first and second quarters of 2014.
The forecast was welcomed by Prime Minister David Cameron as an indication of the success of the coalition's economic policies.
"More evidence that long-term economic plan is working, as OECD says UK growth will be strongest in G7 this year," Mr Cameron said on Twitter.
The OECD prediction suggests a considerably healthier recovery than was expected by the Government's own independent forecasters, the Office for Budget Responsibility, at the time of last December's Autumn Statement, when they expected 2.4% growth in the UK for 2014 as a whole.
The UK GDP figures outstripped those for the US, which the OECD predicted would grow by 1.7% in the first quarter of 2014 and 3.1% in the second, and Germany, where forecast growth of 3.7% in the first quarter fell back to 2.5% in the second, as well as France (0.7% and 1% growth), Italy (0.7% and 0.1%) and Canada (0.5% and 2.4%). After growing by 4.8% in the first three months of 2014, Japan's GDP was predicted to shrink by 2.9% in the next three.
Presenting the OECD's Interim Economic Assessment in Paris, the organisation's deputy secretary-general and acting chief economist, Rintaro Tamaki said: "The gradual recovery in the advanced economies is encouraging, even if temporary factors have pushed down growth rates in the early months of this year, while the slowdown in emerging economies is likely to be a drag on global growth.
"With remaining fragilities in the euro area, and Japan only just beginning to confront its daunting fiscal challenges, it is critical that advanced and emerging economies alike recognise the growing importance of structural reforms to reinvigorate growth."