Latest data from the China Customs Statistics Information Center had revealed that China, which feeds more than 95 per cent of the world's demand for rare earths, had exported 2,196 metric tonnes of the precious metals in April, buoyed by the prevailing low global market prices as well as improved demand from Japan.

Japan accounts for two-thirds of China's rare-earth export market, and any positive development in its economic growth and recovery likewise translates to good returns for China. Japan grew to 3.5 per cent in the first quarter, compared from the 1 per cent at the end of 2012 after six months of contraction.

Japan is buying more because "prices are so low at this point that it's really helped to boost exports," Frank Tang, a rare earths analyst from North Square Blue Oak, told WSJ.

Wang Caifeng, vice chairwoman of the China Association of Rare Earth Industry, said the country's exports of rare earths has sustained an improved momentum since February because stockpiles of Japanese and European companies had started to dwindle.

"Global demand has conspicuously improved," Ms Wang said.

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However, Molycorp believed whatever positive gains in China's rare earths exports momentum could only be temporary.

"It's probably too soon to tell with any significant degree of confidence," spokesman Jim Sims said. "Inventories have been built up over the past several years, and they are returning to more normal levels now... With the continuing volatility in rare-earth volumes and prices, it is a bit early to conclude that this is the start of a real global recovery of demand or just a temporary spike in demand."

Still, "we see these signs as positive."

According to China customs data, China's April exports of rare earths were six times bigger by tonnage from a year ago. It was also a jump of 28 per cent from March.

In the first four months of this year, China had exported a total of 6,112 metric tonnes of rare-earth metals.

Value-wise, China's rare earths exports for the first four months of 2013 was only placed at $136 million, 63 per cent lower from a year ago.