BEIJING -- Exports from China to the U.S. increased markedly last month, thanks to last-minute demand before the latest round of additional tariffs imposed by the world's two largest economies took effect. 

China's General Administration of Customs reported on Friday that exports to the U.S. increased to $46.6 billion in September, up 14% from the previous year. The growth rate expanded from August's 13%. 

Beijing and Washington imposed additional tariffs on each other on Sept. 24, so exports from China in early and mid-September expanded in anticipation, but could decrease in October as a result.

Imports from the U.S. fell to $12.5 billion, down 1% on the year. They decreased for the first time in 21 months from December 2016, except for during the Chinese New Year, which falls at a different time every year. Imports in September were affected by the tariffs the two countries began to impose in July.

Kuiwen Li, a spokesperson at the General Administration of Customs, in a press briefing Friday said, "Friction between China and the U.S. gave our trade some confusion and impact, but we can control both direct and indirect effects."

China's trade balance with the U.S. reached $34.1 billion in September, up 21% on the year, and the highest amount ever for a single month. This indicates that U.S. President Donald Trump's strategy has not yet proven effective.

Akihide Anzai in Tokyo contributed to this report