ZURICH--Swiss exports slowed in November due to weaker demand for the country's machinery, electronic goods and watches, in addition to one work day less.

Exports in November fell 2.9% from a year earlier, in real terms and adjusted for inflation, to 18.06 billion Swiss francs ($18.6 billion), the customs office said Thursday. In nominal terms, exports slipped 0.2%, it said.

Imports reached 14.19 billion francs for declines of 12.1% in real terms and 11.4% in nominal terms.

The trade surplus widened to 3.87 billion francs from 3.23 billion francs in October.

Watch exports in November fell a nominal 4.4%, according to the customs office. Watch exports were worth 2.06 billion francs, for an decline of 4.8% in real terms.

Write to Neil MacLucas at neil.maclucas@wsj.com