* China Jan exports, imports rise, beat forecasts
* Exports rise most since Feb 2015, imports highest in 4 years
* Construction boom fuels heavy commodity imports
* Spectre of Trump protectionism clouding trade outlook (adds analyst comment)
By Elias Glenn and Yifan Qiu
BEIJING, Feb 10 (Reuters) - China posted much stronger-than-expected trade data for January as demand picked up at home and abroad, an encouraging start to 2017 for the world's largest trading nation even as Asia braces for a rise in U.S. protectionism under President Donald Trump.
Trump criticised China, Japan and Germany last week, saying the three key U.S. trading partners were engaged in devaluing their currencies to the harm of U.S. companies and consumers.
But he has not followed through yet on threats to label China a currency manipulator and slap heavy tariffs on Chinese goods, and took a major step on Thursday to improve ties by holding a phone call with President Xi Jinping.
"China's trade data are going to be pretty good in the first part of this year because of the very good run that we had in the last part of 2016," said Louis Kuijs, head Of Asia economics at Oxford Economics in Hong Kong.
"The worry we have is really about U.S. trade policy, which is undeniably turning more protectionist...It is pretty obvious to me that the climate for exports to the U.S. is going to be much harsher in the coming years."
China's imports in January rose at the fastest pace in four years, fueled by a continued construction boom which is boosting demand and global prices for resources from copper to steel, preliminary customs data showed on Friday.
The 16.7 percent bounce easily eclipsed an expected rise of 10.0 percent in a Reuters poll.
China's imports from the United States rose 23.4 percent in January, the fastest pace in at least a year, while its monthly trade surplus with the U.S. dipped to $21.37 billion.
Both Chinese and U.S. data show China's surplus with the U.S. narrowed last year, but it remained well above the sustained level of more than $20 billion that is one of three criteria used by the U.S. Treasury to designate another country as a currency manipulator.
The surplus decreased $20.1 billion to $347.0 billion in 2016, the U.S. Commerce Department said Tuesday, while Chinese data put it somewhat lower.
Led by electronics, China's January exports climbed the most in almost a year, adding to evidence that Asia's long trade recession may be bottoming out.
January shipments rose 7.9 percent, more than twice as much as expected, after 2016 exports slumped nearly 8 percent.