Exports increased 7.5% in September from a year ago, decelerating from an 11.2% rise in the previous month, the customs service agency reported on Tuesday.

The result, which beat the 6.5% consensus estimate from analysts, was driven by a slower 3.4% growth in shipments to the United States in September after increasing 11% in August.

The monthly trade of South Korea, Asia's fourth-largest economy, is considered a bellwether for world trade and is the first to be released among major exporting economies.

Tuesday's data comes amid growing market expectations that the Bank of Korea may cut policy interest rates from 3.50%, the highest since late 2008, at an upcoming rate-setting meeting next Friday as growth concerns overshadow inflation worries.

Slower growth in exports may give BOK officials another reason to cut interest rates after both private consumption and construction investment declined in the second quarter.

"Given how sluggish domestic demand has been, Tuesday's data bodes well for an interest rate cut but we do need to see how board members assess financial stability risks," said Park Sang-hyun, an economist at HI Investment and Securities.

"One thing clear is that it will be difficult for South Korea to see the big, U.S.-bound exports boom it enjoyed in the past few years."

Shipments adjusted for working day differences rose 12.9% from a year earlier.

By destination, exports growth to China, Japan and India all moderated compared to August.

Among products supporting South Korea's export growth were semiconductors, which jumped 37.1% on-year to a record $13.6 billion in September.

Exports of cars increased 4.9%, while shipments of mobile communication devices jumped 19.0%.

Imports climbed 2.2%, falling short of the 3.0% rise forecast by analysts.

The preliminary trade surplus widened to $6.66 billion from $3.77 billion a month earlier.

In September, there were also fewer working days due to a longer break for the Chuseok thanksgiving holiday.