China's monthly trade surplus jumped 16.4 percent in June to $31.6 billion, official data showed Thursday, as exports and imports both rose in the latest sign of recovering strength in the world's second-largest economy.

Exports increased 7.2 percent to $186.8 billion year-on-year, the General Administration of Customs announced, while imports gained 5.5 percent to $155.2 billion.

China is the world's biggest trading nation in goods.

The latest data came with worries over its growth outlook easing following a series of strong indicators in the second quarter, such as industrial production, retail sales and purchasing managers' index (PMI) surveys.

Gross domestic product (GDP) grew 7.4 percent in the first three months of 2014, weaker than the 7.7 percent in October-December last year and the worst since a similar 7.4 percent expansion in the third quarter of 2012.

Customs spokesman Zheng Yuesheng attributed the trade improvement in the second quarter to factors including supportive government policies and a wider global economic recovery.

"We expect the pace of growth in trade will be faster in the third quarter than in the second quarter," he told reporters.

"The stabilisation and recovery trend in trade will further consolidate."

China has since April introduced steps to boost growth, including tax breaks for small enterprises, targeted infrastructure outlays and incentives to encourage lending in rural areas and to small companies, measures dubbed "mini-stimulus" by economists.

"Improving trade figures, plus the encouraging PMI data, point out that China's growth will likely pick up somewhat in Q2 due to the targeted 'mini stimulus' measures," ANZ Bank economists Liu Li-Gang and Zhou Hao wrote in a report.

"We believe that China will achieve 7.5 percent growth in Q2."

China announces second-quarter GDP results on July 16.

June's trade surplus fell short of the median forecast of $36.9 billion in a survey of 21 economists by The Wall Street Journal.

Exports, which accelerated slightly from May's gain of 7.0 percent, fell well short of the median prediction of a 10.0 percent rise.

- Causes for concern -

Imports, which fell 1.6 percent in May, rebounded to surpass the median forecast of a 5.4 percent increase.

Zheng, the Customs spokesman, stressed that "uncertainties" including rising Chinese labour and raw material costs and attempts by industrialised countries including the US to promote their own manufacturing sectors were causes for worry.

In the first quarter, the market share of seven types of Chinese labour-intensive goods such as textile products declined 0.6 percentage points in the US to 44.4 percent and 0.9 percentage point in the EU to 41.2 percent, he said, while competitors including Vietnam, Mexico and India saw their positions rise.

"It remains an arduous task to achieve the 7.5 percent target for full-year growth in trade," he said.

China's trade statistics this year have been erratic, with Beijing reporting an unexpected trade deficit of almost $23 billion in February, which authorities blamed on the Lunar New Year holiday season. That was China's first monthly deficit in 11 months.

And in March, China's trade volumes fell dramatically in a development that analysts blamed on the continued impact of fake over-reporting of exports seen in early 2013.

For the first six months of this year, China's trade surplus declined 4.4 percent to $102.86 billion, as exports rose 0.9 percent to $1.06 trillion and imports gained 1.5 percent to $960 billion, Customs said.

China's leaders say they want to transform the country's growth model to make consumer spending and other forms of private demand the key drivers of the economy.

The new model would steer it away from an over-reliance on huge and often wasteful investment projects that have underpinned decades of past expansion.

Such a makeover is expected to result in slower but more sustainable growth in the long run.

Julian Evans-Pritchard, China economist at Capital Economics, said that June's export growth failed to impress and both exports and imports were likely to slow in July.

"More broadly though, improving conditions in developed markets mean that we expect the export growth to remain healthy going forward, despite today's disappointing data," he wrote in an analysis.

"China is likely to continue to post large trade surpluses," he added.