* Trade to grow 13.5 pct in 2010 after 12.2 pct slump in '09
* Developing country exports to grow 16.5 percent (Changes first paragraph, adds details, byline, link)
By Jonathan Lynn
GENEVA, Sept 20 (Reuters) - International trade will grow by a record 13.5 percent this year, bouncing back from a dismal 2009 and signalling an improvement in economic activity around the world, the World Trade Organization forecast on Monday.
The WTO had predicted in March that trade in merchandise goods would rebound 10 percent this year as the world emerged from recession but revised up its forecast because global trade flows had recovered faster than expected so far this year.
The global commerce umpire now sees world trade growing at a faster rate than at any time since the data were first measured in 1950 as exports and imports surge, especially in China and other emerging economies.
"This surge in trade flows provides the means to climb out of this painful economic recession and can help put people back to work," said WTO Director-General Pascal Lamy.
"It underscores, as well, the wisdom governments have shown in rejecting protectionism," he said in a statement.
In 2009, exports worldwide contracted 12.2 percent -- the biggest fall since before World War Two -- as demand for goods shrivelled in the economic crisis, and finance to fund trade dried up due to the credit crunch.
WTO economists expect developing economies and countries in the former Soviet Union to see exports expand by a massive 16.5 percent after contracting 7.8 percent in 2009. Rich countries are set to enjoy an expansion of 11.5 percent after a slump of 15.3 percent last year.
Trade growth is likely to be less impressive in the second half of this year than in the first six months, as the expiry of fiscal stimulus measures and post-recession restocking restrains output growth, the WTO said.
The new forecast could also need to be corrected downwards if unforeseen financial or economic shocks trigger another downturn.
But the forecast of record trade expansion could prove too cautious if economic growth turns out to be better than expected in the second half of the year, it said.
Trade typically outpaces the overall economy, both rising and falling faster than gross domestic product. (For full WTO statement go to http://link.reuters.com/vaz54p ) (Editing by David Stamp)