* Reiterates full-year sales to grow 2 percent
* Strong U.S. growth continued in April and May
* Western Europe revenue down slightly in first 5 months
(Adds details, background, shares)
LONDON, June 29 WPP Plc (WPP.L), the world's biggest advertising group by sales, said the United States and southeast Asia had driven an acceleration in growth in May and June, and reiterated 2010 like-for-like sales should grow 2 percent.
The group, whose ad agencies include JWT and Ogilvy & Mather, said the positive trend should continue, helped by events including the FIFA soccer World Cup, the Winter Olympics and the U.S. mid-term elections.
In the first five months of the year, like-for-like sales grew 2 percent, with May sales up well over 5 percent.
Sales were up in all regions apart from western Europe, where France and the Netherlands were particularly challenging, WPP said in a trading update on Tuesday.
"It has been a pretty bumpy ride -- and it is not over yet," WPP said.
WPP shares fell 1.2 percent to 649.5 pence by 1121 GMT, in line with the European media index .SXMP. The shares have rallied about 10 percent this year so far, outperforming the index by 15 percent.
Sorrell told Reuters last week the British advertising group's forecast for like-for-like revenue to rise by 2 percent this year was probably too pessimistic. [ID:nLDE65N1O2]
The chief executive of U.S. rival Interpublic (IPG.N) said last week he was cautiously optimistic the market was turning around, as long as Europe's economic woes were contained and did not spill over into global markets. [ID:nLDE65M2CF] (Reporting by Georgina Prodhan; Editing by David Holmes)