ZURICH, June 20 (Reuters) - Swiss exports fell in May, with a particularly sharp decline in watches, pharmaceuticals and chemicals, the Federal Customs Office said on Thursday.
Exports from Switzerland fell by a real 5.2 percent in May to 17.434 billion Swiss francs ($18.96 billion), but rose by a real 1.7 percent when adjusted for seasonal factors.
Exports of pharmaceuticals and chemicals, the country's biggest export category, fell 6.8 percent while machines and electronic devices were down 3.2 percent and watch exports dropped 4 percent.
Swiss exports have been supported by a cap the central bank imposed on the soaring franc currency in 2011, but have suffered from sluggish demand in Europe, the country's biggest trading partner.
The trade surplus widened to 2.224 billion francs in May from 1.698 billion a month earlier.
The Swiss National Bank is expected to reaffirm its commitment to defend its lid on the safe-haven currency at its June monetary policy assessment expected at 0730 GMT. ($1 = 0.9194 Swiss francs) (Reporting by Emma Thomasson; Editing by Andrew Heavens)