Japan on Monday posted its first half-year trade surplus since the 2011 Fukushima nuclear disaster, after the accident sent energy import bills soaring and led to a string of deficits.

The world's third largest economy logged a January-June surplus of 1.8 trillion yen ($17 billion), against a 1.69 trillion yen deficit in the same period last year, the finance ministry said.

A sharp drop in oil and gas prices took pressure off Japan's trade balance, but exports still struggled to make headway with a sharp rise in the yen weighing on profits among some of Japan's biggest firms.

The six-month surplus was the first since the July-December 2010 period, trade ministry data showed.

The Japanese economy, which was already struggling at that time, was hammered by the quake-tsunami disaster that sparked the accident at Fukushima.

The atomic disaster, the worst since Chernobyl in 1986, forced the shutdown of reactors in resource-poor Japan, which turned to thermal power plants and pricey fossil fuel imports to keep the lights on.

Falling energy prices have been good news for Japan's trade balance but its export picture remains shaky with the value of shipments to key markets China and the United States both down.

China-bound shipments dropped 10.0 percent in June, marking a fourth straight monthly decline, while they were down 6.5 percent to the US, led by a fall in auto and steel exports.

Shipments to China and the US also fell over the six-month period.

"The sharp strengthening of the exchange rate since the start of the year continued to depress trade values in June," said Marcel Thieliant from research house Capital Economics.

But the volume of trade has stabilised and the yen's surge was cooling off, he added.

"As such, import prices should pick up again, resulting in a renewed decline in the trade surplus," he added.

The yen, often seen as a safe haven currency, surged on fears over the state of the global economy and more recently on concerns over Britain's vote last month to quit from the European Union.

Japan's economy has been struggling to gain traction with a string of weak readings and sagging business confidence heaping pressure on Tokyo and the Bank of Japan to counter the downturn.

The central bank this week holds its latest meeting where it is expected to announce fresh monetary easing measures, as Tokyo compiles a promised stimulus package reportedly worth as much as 20 trillion yen.

The BoJ's massive monetary easing plan is a cornerstone of efforts to bring an end to years of the deflation that held back growth in the once-powerhouse economy.

But Prime Minister Shinzo Abe's growth policies, dubbed Abenomics, have faltered.

The plan -- a mix of massive monetary easing, government spending and red-tape slashing -- brought the yen down from record highs and made Japan's exports more competitive but that has not been enough to deliver consistent growth.