London Metal Exchange (LME) prices drifted mostly lower by the close of open-outcry trade on Tuesday but remained in ranges despite a firmer dollar and talk of Chinese copper sales, dealers said.
Three months futures ended the day at $3,956 a tonne, down $10 from Monday's kerb close.
"Aluminium looked like it was hit by fund selling early on and the same is true in copper," one dealer said.
"Copper looks supported at $3,950 and then at $3,900," he said.
Dealers said China's State Reserves Bureau (SRB) had sold 40,000 tonnes of copper on the Shanghai Futures Exchange, and some forecast it might sell around 100,000 tonnes to try to reduce prices.
The SRB is expected to auction 11,000-20,000 tonnes of copper next week, dealers said on Tuesday.
"The SRB doesn't tell people what it is doing and my worry is why we are hearing so much noise about their deliveries," one physical trader said.
"They are trying to scare prices lower by talking about delivering material rather than actually dumping it all on the market because in the future they may have to buy it all back," he added.
The market shook off a stronger dollar as the US currency hit a two-year high against the euro.
"The short-term dollar target against the euro is $1.16. The euro may strengthen again towards the end of year and will pick up further in the new year," the first trader said.
Aluminium held below last week's 10-year high of $2,040 but were seen firmly supported by high energy costs.
"Aluminium has been stuck in tight ranges. The market is pretty dead and we are just not seeing great volume," another dealer said.
"But the funds are still keen and, as they say, the trend is your friend," the dealer added.
Three months was at $2,011, down from $2,023. Nickel was at $12,275, up $150, while zinc was at $1,580, up $5.
Tin was at $6,300, down $100, while lead was at $972, down $4.