(Adds analyst comment, updates prices)
BEIJING, Aug 10 (Reuters) - Copper prices moved higher in Shanghai and London on Friday and were set to end the week in positive territory as the prospect of strikes at copper mines in Chile drew nearer.
The workers' union at BHP's Escondida copper mine, the world's largest, says the company must alter its negotiating strategy and improve its contract offer during a final phase of talks if it hopes to avoid a strike.
Meanwhile, the main union at Lumina Copper's Caserones mine said on Wednesday a last round of labour negotiations had broken down and that a strike was imminent.
"The last negotiating period (at Escondida) is fast coming to an end, with the two parties still far apart. This should see operations impacted in the not too distant future," ANZ wrote in a note.
Copper has also received a boost from China's move to impose a 25 percent import tariff on scrap copper from the United States, one of its biggest suppliers of the material. "This is likely to see China importing more refined metal," the bank added.
* LME COPPER: Three-month copper on the London Metal Exchange nudged up 0.2 percent to $6,207.50 a tonne, as of 0406 GMT, extending a 0.8 percent gain in the previous session.
* SHFE COPPER: The most traded October copper contract on the Shanghai Futures Exchange was up 0.3 percent to 49,840 yuan ($7,290.07) a tonne by the mid-session interval and is on course for a weekly gain of 1.1 percent.
* COPPER OPTIONS: The ShFE says it is planning to introduce a market-maker system for its upcoming copper options contract in order to ensure liquidity.
* ALUMINIUM: Three-month aluminium on the LME was up 0.7 percent at $2,083 a tonne, after ending down 1.3 percent in the previous session on profit-taking. ShFE aluminium was down 0.6 percent at 14,665 yuan a tonne.
* ALUMINIUM STOCKS: On-warrant stocks of aluminium available to the market in LME-registered warehouses have fallen to 832,775 tonnes, the lowest since 2007. <MALSTX-TOTAL>
* OPEN INTEREST: Market open interest in ShFE aluminium rose to its highest since April on Thursday. Long positions on the October contract rose by a massive 15,237 lots to 96,974 lots, while shorts were up by 17,853 lots to 106,718 lots. Citic Futures is the top position holder for each.
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* Asian stock markets fell on Friday amid heightened global trade tensions, while currency markets were whipsawed by a searing selloff in Russia's rouble after the United States slapped on new sanctions, and as economic worries sent the Turkish lira tumbling.
Three month LME copper
Most active ShFE copper
Three month LME aluminium
Most active ShFE aluminium
Three month LME zinc
Most active ShFE zinc
Three month LME lead
Most active ShFE lead
Three month LME nickel
Most active ShFE nickel
Three month LME tin
Most active ShFE tin
ARBS ($1 = 6.8367 Chinese yuan)
(Reporting by Tom Daly; Editing by Gopakumar Warrier)