LONDON, Dec 15 (Reuters) – Copper prices scaled 3-week highs on Friday alongside U.S. equities after the New York open and as expectations of strong demand in top consumer China were reinforced by data showing firm industrial activity. Traders said rising stock market indices on Wall Street had boosted sentiment and sparked a wave of buying on industrial metals markets. Benchmark copper on the London Metal Exchange was up 1.3 percent at $6,879 a tonne at 1532 GMT from an earlier $6,884, the highest since Nov. 28. Prices are up nearly 25 percent so far this year. “Fundamentals are pretty strong on the back of the global economy and China,” said Societe Generale analyst Robin Bhar, adding that copper had established a floor at $6,500. “We may see some volatility over the new year and we may have to wait until after the Chinese new year in February to see clear where China demand is going.” INDUSTRY: China’s industrial output, highly correlated with copper prices, rose 6.1 percent in November from the same period last year, surpassing analysts’ estimates for a rise of 6.0 percent. HOLIDAY: Industrial activity in China typically slows ahead of the country’s Lunar New Year holiday, which in 2018 is on Feb. 15-21. INDICES: The first few working days of January will see a rebalancing of commodity indices, which given the rally in industrial metals this year may mean sellers dominate. SLOWING: However, analysts at BAML noted that activity in China had been slowing for a while. “Indeed, 3 out of 6 sectors are at present contracting and recent history suggests that a weakening of activity in one more sector would trigger year-on-year price declines. As such, we remain cautious copper into year-end,” they said in a note. ZINC: Prices rose 0.7 percent to $3,209 from an earlier $3,219, the highest since December 4 on concern the tightness seen this year would also be a feature of the market next year. ZINC SPREADS: However, on the LME market, receding concerns about availability have seen the premium for the cash over the three-month contract MZN0-3 fall to zero from above $90 a tonne in October, the highest since December 2006. LEAD: Prices gained 1.2 percent to $2,517 a tonne. It has been boosted in recent weeks by the expectation of strong demand from auto battery makers during the winter.