Japan's exports grew 40.4 percent in April from a year earlier as demand in Asia and the United States remained robust in yet another sign that the export-oriented economy is on track for recovery, Finance Ministry data showed Thursday.

But economists and policymakers are cautious about the future because the sovereign debt debacle in Europe and the resultant tumult on global financial markets could start to hurt Asia, Japan's biggest export destination.

April exports came to ¥5.89 trillion, up for the fifth straight month. They were buoyed by strong demand for automobiles, chips and digital memory in Asia, especially China, but the rate of growth slowed from the previous month's 43.5 percent.

Imports rose 24.2 percent to ¥5.15 trillion, increasing for the fourth consecutive month, according to preliminary ministry data.

"Exports will likely remain solid for a while, but the outlook is increasingly uncertain," said Yoko Takeda, a senior economist at Mitsubishi Research Institute.

She cited worries over the impact of the European debt crisis as well as a possible further rise of the yen.

The debt problem is "the largest factor" clouding prospects, Takeda said, because it could slow the economy in China, leading to a knock-on effect on Japan's export-backed recovery.

Even if the Asian economy remains bullish, however, a continued rise by the yen against the euro and dollar could have a significant impact on the trade balance, she said.

The trade balance in April posted a surplus of ¥742.26 billion, marking the 13th consecutive month in positive territory.

The surplus logged a fifteenfold jump, the second-largest increase since officials began compiling comparable data in 1980. The hefty increase, however, largely reflects a drop in April 2009, when the economy was still reeling from the 2008 financial crisis.

In trade with China, Japan suffered a deficit of ¥21.27 billion.