The surplus in the current account, the broadest measure of Japan's trade with the rest of the world, stood at 407.5 billion yen ($5.3 billion) in August before seasonal adjustment, finance ministry data showed.

The result was lower than expectations of a 446.9 billion yen surplus in a survey of economists by Dow Jones Newswires and the Nikkei.

In August, Japan saw a trade deficit of 694.7 billion yen, from a trade surplus of 170.6 billion yen a year earlier.

Japan's exports rose 4.0 percent in August -- a sign of some recovery from the twin March disasters, which devastated the economy, particularly in north-eastern Japan.

But imports jumped 22.4 percent, partly due to higher oil prices as Japan's need for fossil fuels has increased as it compensates for the shutdown of most of its nuclear reactors after the Fukushima atomic accident.

The current account measures trade in goods, services, tourism and investment. It is calculated by determining the difference between Japan's income from foreign sources against payments on foreign obligations, and excludes net capital investment.