Britain's Office for National Statistics said the national trade deficit for September came to $4.3 billion, a sharp decrease from August.
The trade gap had been $6.3 billion in the previous month, the ONS said.
In the third quarter, Britain posted a trade deficit of $13.5 billion. It was $16 billion in the second quarter.
Excluding oil "and erratic items" of trade, the volume of exported goods rose 4.1 percent in the third quarter from the second. The volume of imports over the same period fell 0.3 percent, the ONS said.
The statistics were released without accounting for recent shifts in prices. A report that includes adjusted figures is scheduled for release in December.