New Delhi, Dec. 31 -- Chinese factory activity expanded for the first time in eight months in December, as orders picked up ahead of holidays and builders rushed to finish projects, according to surveys released Wednesday.

The official purchasing managers index for manufacturing, a monthly survey of companies, rose to 50.1 this month, the National Bureau of Statistics reported. That was just above the 50 cut off for expansion versus contraction on a scale up to 100. Another, private sector, survey also was at 50.1 for December.

The better-than-expected readings partly reflect easing pressure due to an extended truce in trade tensions with the U.S. They also suggest manufacturers ramped up production ahead of New Year holidays, when many...