Three-month copper on the London Metal Exchange gained as much as 1.2% to $5,991 a tonne, its highest since May 28 and stood at $5,980.50 as of 0701 GMT. Nickel also touched its highest since May 28 at $12,255 a tonne.
The U.S. Fed on Wednesday left interest rates unchanged as widely expected, but said the case for lower rates was building, suggesting it could ease monetary policy as early as next month amid rising trade tensions and concerns about weak inflation.
The dollar index eased against a basket of six major currencies on Thursday after losing more than 0.5% overnight, making dollar-denominated metals cheaper for holders of other currencies.
"A weaker USD offset some concerns about the upcoming U.S.-China trade talks. Reports of the call between the two presidents suggested that their meeting at the G20 would only cover strategic issues, raising concerns that an agreement was still some way off," said ANZ in a note.
FUNDAMENTALS
* LME: In a broad LME price rally, aluminium climbed for a third straight day and was trading up 0.5%, while zinc gained 1.3%, lead rose 1.1% and tin advanced 0.9%.
* SHFE COPPER: The most traded August copper contract on the Shanghai Futures Exchange closed up 0.2 percent at 46,930 yuan ($6,833.84) a tonne.
* CHILE: Unions at Chile's Codelco were scheduled to discuss an improved contract offer that the world's top copper producer hopes will bring an end to a strike at its huge Chuquicamata deposit.
* TRADE TALKS: U.S. Trade Representative Robert Lighthizer said he expected to meet with China's vice premier and chief trade talk negotiator Liu He in Osaka along with U.S. Treasury Secretary Steven Mnuchin before Trump's meeting there with Xi.
* CHINA FIRM: Upcoming trade talks between China and the United States are unlikely to immediately resolve major disagreements between the two sides, but could start a new phase in negotiations, Chinese state media said.
* LITHIUM: Australia's Altura Mining said on Thursday its former biggest investor and one-time suitor, China's Shaanxi J&R Optimum Energy, has sold its entire remaining 11.8% stake in the lithium miner.