China issued a raft of upbeat data today showing the economy got off to a strong start to 2017, supported by strong bank lending, a government infrastructure spree and a much-needed resurgence in private investment.

Solid growth is welcome news for China's policymakers as they turn their focus to containing risks from a sharp build-up in debt ahead of a major leadership reshuffle later this year.  

But economists are not sure how long the pace can be sustained as the central bank takes a tighter stance on credit and exporters brace for a surge in US protectionism. 

Chinese fixed-asset investment expanded more strongly than expected in the first two months of the year as growth in private investment more than doubled from 2016.

Surging demand for steel for new roads, bridges and homes lifted factory output. 

That added to readings last week showing robust imports, particularly of commodities such as iron ore, and a sharp rise in producer prices which is boosting industrial profits.

China has cut its growth target to around 6.5% this year to give policymakers more room to push through painful reforms to reduce financial risks created by years of debt-fuelled stimulus. 

The world's second-largest economy grew 6.7% last year, the slowest pace in 26 years. 

Economists believe that China's first-quarter economic growth could accelerate to 7% year-on-year, from 6.8% in the last quarter of 2016. 

But many other China watchers expect that pace will begin to slow starting in spring as the payoff from last year's stimulus spree begins to fade.

Analysts singled out an unexpectedly strong rebound in investment as particularly encouraging for China's outlook. 

Fixed-asset investment growth accelerated to 8.9% in January and February from the same time last year, largely due to strong property and infrastructure construction. 

Economists had expected investment growth of 8.2%, quickening from 8.1% in the whole of 2016. 

Growth in private investment quickened to 6.7%, more than twice the pace of last year, suggesting private firms are growing more optimistic about the business outlook.

Private investment had cooled sharply last year, with many smaller firms facing tough access to financing, tight profit margins and a crowding out by big state companies. 

Private investment accounts for about 60% of overall investment in China.

Figures today also showed that industrial output rose 6.3%, slightly more than expected and the best pace in nearly a year. 

China's steel mills are churning out as much metal as possible, enjoying their best profits in years, even as they worry that a year-long rally in prices is running out of steam, executives said. 

China combines January and February activity data in a bid to smooth out seasonal distortions caused by the timing of the long Lunar New Year holidays, which began in late January this year but fell in February last year.

While activity data suggested generally resilient growth, analysts pointed out two potential areas of concern. 

Property data was mixed, with some hints that the sector may be showing signs of heating up again, despite a slew of government curbs since October to tame sharp home price rises. 

China's property sales by area surged 25.1% in the first two months from a year ago, well above the annual rate last year which was the fastest in seven years. It was also a marked surge from December.

Real estate investment growth moderated but only slightly, to 8.9% from 11.1% in December, according to Reuters' calculations. It rose 6.9% in all of 2016. 

A rebound in the sector could risk another round of cooling measures which could drag on broader growth.

China's retail sales also disappointed. Sales grew 9.5% in the first two months of the year, the slowest pace in nearly two years and cooling from 10.9% in December. 

China's economic outlook is also being clouded by increasing fears of protectionism under US President Donald Trump. 

Trump plans to host President Xi Jinping at a summit next month, according to media, as his administration seeks to smooth relations which have got off to a rocky start. 

During the election campaign, Trump had threatened to label China a currency manipulator and impose huge tariffs on imports of Chinese goods. 

He has not followed through on either move yet, but the US Treasury will issue its semi-annual currency report in April.