* Brazil May trade surplus at $3.529 billion
* Currency weakened in May, helping industry (Recasts, adds details)
SAO PAULO, June 1 (Reuters) - Brazilian exports grew at twice the rate of imports in May, giving the country its strongest trade surplus yet for the year.
Brazil posted a trade surplus BRTBAL=ECI of $3.529 billion in May, the trade ministry said on Wednesday.
In April, Brazil's trade surplus totaled $1.86 billion, the trade ministry reported last month.
May was the first month since January in which Brazil's currency, the real, weakened. The month also saw more working days than any other so far this year.
Exports expanded by about 15 percent in May from April, compared to the 7.5 percent expansion in imports.
That growth took exports to $23.211 billion in May from $20.173 billion in April. Exports totaled $17.702 billion in the year-ago month.
Imports rose to $19.682 billion in May from $18.310 billion in the previous month and $14.254 billion in May 2010.
The strength of Brazil's currency, the real BRBY, has been a worry for exporters, who have found their products costlier to sell abroad. The government has tried a slate of measures to brake the real's gains.
But renewed uncertainty about the global economy, including the strength of the U.S. recovery and a sovereign debt crisis in Europe, has helped weaken the real recently, giving policy-makers some relief.
In 2010, Brazil's trade surplus dwindled to $20.3 billion from $25.3 billion the previous year as the fastest economic expansion in nearly three decades, coupled with a strong currency, increased demand for imports.
Brazil is a major exporter of food and mineral commodities, including soybeans, beef and iron ore. (Reporting by Daniela Machado and Luciana Lopez. Editing by W Simon )