Euro zone factory activity retreated further into contraction territory in December as production decreased for the first time in 10 months, dampened by accelerating declines in new orders, a survey showed on Tuesday. The HCOB Eurozone Manufacturing Purchasing Managers' Index (PMI), compiled by S&P Global, fell to 48.8 in December from 49.6 in November, marking its lowest reading in nine months and lower than a preliminary estimate of 49.2.