Prices have staged a year-end rally, rising almost seven percent in the past month, on evidence of China's renewed growth momentum in November and signs of US manufacturing recovery.
"Copper is a China and US story. Right now China is in recovery and the US is in recovery. It's still a weak recovery but we don't think the price will drop, so any good news from the liquidity side or the macro side will help the price go higher," said Henry Liu, head of commodity research at Mirae Asset Securities in Hong Kong.
"No doubt about it, the liquidity from the US Fed is a good driver for prices," he added.
Three-month copper on the London Metal Exchange traded at $8,112.75 a tonne by 0709 GMT, up 0.12 percent from the previous session, when it logged small losses.
Copper prices are up more than 6 percent this year and stay within reach of almost two-month highs at $8,159 hit on Monday.
The most-traded March copper contract on the Shanghai Futures Exchange rose 0.14 percent to close at 57,980 yuan ($9,300) a tonne.
The dollar remained broadly under pressure on Wednesday as markets geared up for more Fed stimulus, underpinning metals. Dollar-priced commodities are cheaper for holders of other currencies when the greenback is weaker.
The US Federal Reserve is expected to announce a new round of Treasury securities purchases at its policy meeting that concludes later in the day.
Markets have generally priced in a fix to negotiations to avert the "fiscal cliff" of $600 billion worth of tax cuts and spending increases that expire early next year and threaten to tip the world's second biggest economy into recession.
But until a deal is reached, traders expect a ceiling to remain over prices.
Talks intensified on Tuesday as President Barack Obama and US House of Representatives Speaker John Boehner spoke by telephone after exchanging new proposals, but a spokesman said Boehner did not view them as acceptable.
Sentiment also firmed in the wake of stronger economic sentiment in Germany spurred by encouraging US economic data, entering positive territory for the first time since May.
European stock futures pointed to a fractionally higher open on Wednesday, on expectations for the US Federal Reserve to announce more stimulus to support the economy and on hints of progress in US budget talks.
ALUMINIUM PREMIUMS DROP
Japanese buyers have agreed an aluminium premium for some January-March shipments of $240 per tonne with Rio Tinto Alcan , down from a record $254 to $255 in the previous quarter, three sources directly involved in the talks said on Wednesday.
Rio Tinto Alcan offered the premium of $240 last month, lower than Alcoa's offer of $247 and BHP's $249, two of the sources said.