Japan's economy rebounded in July-September as efforts to restore supply chains and recover lost output in the wake of the March disasters helped it post its first expansion in four quarters.

Automakers and other key industries boosted output to meet pent-up demand after the earthquake, tsunami and nuclear crisis, but analysts warned that a strong yen and a global slowdown will weigh on the recovery.

The world's third-biggest economy grew by an annualised 6.0 percent in the July-September quarter, preliminary data showed Monday, the fastest pace since January-March 2010. The result was largely in line with market expectations.

On a quarterly basis, gross domestic product grew 1.5 percent in July-September, the data showed, compared to a 0.3 percent on-quarter contraction in April-June. The data is subject to constant revision, however.

"The positive growth came on the back of rapid restoration of (nationwide) supply chains after the disasters," said Motohisa Furukawa, the country's economic and fiscal policy minister, warning however that the recovery is moderating.

Recent flooding in Thailand has also complicated the outlook for Japanese firms from Sony to Toyota, forcing plant closures that have affected global production and prompting many to withdraw their full-year earnings forecasts.

"We have to pay adequate attention to downside risks, such as possible deterioration in foreign economies, rapid appreciation in the yen and the impact of damage from the Thai floods," Furukawa said at a news conference

Improving exports were the biggest contributor to growth in the third quarter, followed by private consumption.

On a quarterly basis, exports were 6.2 percent higher, while private consumption gained 1.0 percent.

The March disasters left 20,000 people dead or missing, devastated large areas of the northeast and sparked a nuclear crisis at the Fukushima nuclear plant.

The damage and devastation brought by the tsunami also shattered crucial component supply chains, forcing companies to shut down factories, slowing the nation's output and exports as the economy tipped into recession.

While Japan's producers have raced to restore output more quickly than expected, recent quarterly earnings have shown those efforts are being undermined by a strong yen that erodes repatriated profits, while demand wanes because of a global economic slowdown.

The yen has recently hit post-World War II highs against the dollar amid heightened market volatility as the eurozone crisis deepened, despite efforts by Japanese authorities to stage yen-weakening market interventions.

Japan "achieved temporary high growth in the process of normalising production, exports and consumption that had been lost after the Great East Japan Earthquake," said Naoki Murakami, chief economist at Monex Securities.

However, leading indicators have showed the recovery is slowing, he noted.

Data last week showed Japan's core private-sector machinery orders dropped 8.2 percent in September on-month, as uncertainty about the global economy causes firms to rein in spending.

"The economy is expected to slow to low growth from the October-December quarter because of the yen's strength that is weighing down corporate earnings as well as a delay in reconstruction demand," said Murakami.

Analysts say the economic impact of flooding in Thailand will emerge in fourth-quarter data, with exports to Europe also seeing a slowdown.

"The economy will struggle to grow at anywhere near this pace in Q4," said Capital Economics in a research note.

Japan is expected to soon pass a 12.1 trillion-yen ($156 billion) budget to finance post-quake reconstruction and boost the economy.