(Adds China data, Alcoa, and updates prices)
By Manolo Serapio Jr
MANILA, Aug 8 (Reuters) - London copper ticked higher on Wednesday after the dollar weakened against a basket of major currencies as its recent rally fuelled by U.S.-China trade tensions appeared to fizzle.
Three-month copper on the London Metal Exchange was up 0.3 percent at $6,194 a tonne by 0726 GMT, gaining for a second session in a row.
The most-traded October copper contract on the Shanghai Futures Exchange rose 0.3 percent to close at 49,530 yuan ($7,273) a tonne.
The dollar inched down versus a basket of currencies, making dollar-denominated assets like copper cheaper for holders of other currencies, even after the U.S. Trade Representative's office said the U.S. would begin collecting 25 percent tariffs on another $16 billion in Chinese goods later this month.
Despite threats of labour strikes at big copper mines including Escondida in Chile, copper prices have fallen nearly 15 percent this year.
"The market is still trading on macro risks, especially the trade frictions between the United States and China," said Chris Wu, analyst, CRU consultancy in Beijing.
Despite the "signals from the unions at Escondida and some large copper mines in Chile and Peru, we haven't seen a serious strike so far," she said, adding that the global copper market "is in no shortage of supply".
* ESCONDIDA: The union at Chile's Escondida copper mine, the world's largest, said that BHP must alter its negotiating strategy and improve its contract offer during the final phase of talks if it hoped to avoid a strike.
* CHINA ALUMINIUM: China's aluminium exports rose to their second-highest level on record in July, as a weaker yuan and a still-favourable price arbitrage to international markets outweighed the imposition of U.S. import tariffs and growing trade tensions.
* CHINA COPPER: China's imports of copper concentrate rose to an all-time high last month as Chinese smelters ramped up purchases to feed their growing capacity and take advantage of high processing charges.
* ALCOA WALKOUT: Alcoa workers in Western Australia have walked out indefinitely over an enterprise agreement dispute with the aluminium maker, the Australian Workers' Union said.
* OTHER METALS: Nickel rose as much as 1.5 percent to $14,055 a tonne, to a one-week high. Zinc gained 0.5 percent to $2,612 a tonne, and aluminium was flat at $2,038.
* SHANGHAI LEAD: Shanghai lead climbed 2.6 percent to settle at 18,455 yuan a tonne. ANZ analysts said in a note there was market speculation that processors of recycled metal are cutting output on weak margins with smelters in Hunan, Yunnan halting production at the end of last month. Smelters in Guizhou, Henan and Hebei provinces halved output.
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 = 6.8097 Chinese yuan)
Reporting by Manolo Serapio Jr.; Editing by Eric Meijer and Sherry Jacob-Phillips