MANILA, June 8 (Reuters) - London copper retreated on Friday after a six-day rally that pushed the metal to its strongest in 4-1/2 years in the previous session, amid worries over potential supply disruptions at the world's biggest copper mine where wage talks are underway. The union of workers at the BHP-operated Escondida copper mine in Chile last week kicked off labor negotiations with a contract proposal that includes a bonus of about $34,000 per worker, sparking fears of a possible strike. Three-month copper on the London Metal Exchange was down 1.4 percent at $7,230 a tonne by 0217 GMT. The contract touched $7,348 on Thursday, its loftiest since January 2014, and has risen nearly 5 percent so far this week, the most since mid-February. ANZ senior commodity strategist Daniel Hynes said the Escondida union's bonus proposal compares with BHP's offer of $21,300, "therefore, both parties reaching a deal looks difficult at the moment, leaving room for a strike." "The union has enough cash to go on a strike of 44 days. This deal is important for the other wage contract renewals too. We see prices remaining volatile until they reach an agreement," Hynes said in a report this week. * SHANGHAI COPPER: The most-traded August copper contract on the Shanghai Futures Exchange slipped 0.2 percent to 53,840 yuan ($8,411) a tonne. * CHINA DATA: China is scheduled to release its trade data later in the day, with exports and imports expected to have grown at a firm pace in May but slightly slower than the previous month. * IMPORTS: In April, China's copper imports rose 2.8 percent from the previous month to 442,000 tonnes. * CHILE OUTPUT: Chile's copper production in April jumped 6.4 percent from the same month a year earlier, Chilean copper commission Cochilco said, boosted by increased output at large, privately held mines in the world's top copper producer. * DOLLAR: The dollar wallowed near a three-week low against peers as U.S. Treasury yields fell sharply, while the euro's recovery remained intact amid expectations that the European Central Bank would begin unwinding it stimulus programme. * TRUMP: Leaders of the Group of Seven rich nations headed for a summit in Canada more divided than at any time in the group's 42-year history, as U.S. President Donald Trump's "America First" policies risk causing a global trade war and deep diplomatic schisms. * U.S. DATA: The number of Americans filing for unemployment benefits unexpectedly fell last week, pointing to a further tightening in labor market conditions. * OTHER METALS: Other metals also slipped, with LME lead down 1.9 percent at $2,482.50 a tonne, after hitting a three-month high on Thursday, and zinc dropping 0.9 percent to $3,155.50. Shanghai lead fell 1.4 percent to 20,375 yuan a tonne and nickel lost 1.9 percent to 115,680 yuan.