ZURICH, Switzerland — Swiss exports climbed to a record high last year despite a strong franc and geopolitical jitters, led by chemicals and drugs, customs data released on Tuesday showed.

Exports rose a nominal 5.7 percent — the strongest rate since 2010 — and a real 1.2 percent to 233.1 billion Swiss francs ($235 billion).

Imports surged even more to surpass 200 billion francs, reducing the annual trade surplus to 31.3 billion francs. The trade surplus in December narrowed from the month earlier.

The Swiss National Bank has adopted negative interest rates and said it is ready to intervene on foreign exchange markets to rein in the franc, which it calls highly valued and thus a threat to the export-led economy. A strong franc makes Swiss products more expensive abroad and competing imports cheaper.

SNB officials said this month they saw no reason to depart from their expansive policy given heightened political jitters in a fragile market.

All major sectors contributed to the export boom last year. The biggest contribution came from the chemical and pharmaceuticals sector, which includes Novartis, Roche and Lonza. Exports of medicines grew a nominal 8.9 percent during the year.

Shipments of machinery and electronics grew 4.6 percent, while watchmakers, including Swatch Group and Richemont, saw foreign deliveries swell by a nominal 6.3 percent.

Among the three main export markets, North America stood out with a surge of 11.6 percent, fuelled by record deliveries to the United States.

Exports to the United Kingdom fell 23 percent, the biggest decline in 30 years, while imports from Britain jumped 27 percent. The reason for the drop in exports was not clear, but customs officials said declining drugs sales made up most of it.

By Michael Shields.