By Naveen Thukral
SINGAPORE, June 5 (Reuters) - Copper rose for a fourth consecutive session on Tuesday, climbing to its highest in almost six weeks, on support from potential supply disruptions amid wage talks at the world's biggest mine.
Three-month copper on the London Metal Exchange was up 0.3 percent at $6,997 a tonne as of 0712 GMT, after rising to $7,006 a tonne, the highest since April 26, earlier in the session.
The most-traded copper contract on the Shanghai Futures Exchange closed up 0.8 percent to 52,290 yuan ($8,163.81) a tonne.
The union at BHP's Escondida mine in Chile said on Friday that it had started the latest round of negotiations with a proposal that includes a bonus of about $34,000 per worker.
The closely-watched talks come little more than a year after failure to reach a labour deal at the mine led to a 44-day strike that jolted the global copper market.
"Copper led the sector higher as concerns of supply disruptions resurfaced," ANZ said in a note.
"Union leaders at the Escondida copper operation sent their most ambitious wage proposal to owners BHP Billiton, raising the possibility of strike action later this year."
Concerns over demand in China, the world's top industrial metals consumer, weighed on the market. China's economic growth could slow to about 4.5 percent over the medium term, Fitch Ratings said, adding that it expected oil and metals prices to fall by 5-10 percent from its baseline scenario because China is such a large consumer.
TECHNICALS: LME copper may extend its gain to $7,016 per tonne, as suggested by its wave pattern and projection analysis. The metal is riding on a wave C from $6,727. This wave is capable of travelling to $7,016, its 100 percent projection level.
SPECULATORS: Positioning by speculative investors in LME copper was largely neutral, brokers at Marex Spectron said.
TOROMOCHO MINE: China's Chinalco said it had begun a $1.3 billion expansion of its Toromocho mine in Peru, which it said would raise copper output by 45 percent by 2020. China's official Xinhua news agency said Chinalco aimed to bring annual refined copper output to 300,000 tonnes.
LEAD: Shanghai lead prices rose as much as 4 percent on Tuesday to their highest since November 2016 after the government in China's northern province of Hebei announced environmental inspections on the acid industry.
The most-traded lead contract on the Shanghai Futures Exchange hit a high of 20,680 yuan a tonne, the most since Nov. 29, 2016. The market finished up 3.6 percent at 20,600 yuan a tonne.
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 = 6.4051 Chinese yuan)
Reporting by Naveen Thukral; editing by Richard Pullin and Subhranshu Sahu