Copper prices set successive record highs in Friday's London Metal Exchange (LME) trading, with the market focused on a looming Chinese short position.
Three months hit a peak of $4,243 a tonne and ended the rings at $4,200, from Thursday's close of $4,145.
Speculation over a Chinese short position that might entail losses of $200 million has increasingly driven the market in the past week, and dealers expected further gains in the short term.
"The momentum to advance is still strong, although the same can be said about technical pressures to sell," a dealer said.
Dealers said the market was overbought but had few sellers, while fund-based buyers added to long positions.
China's State Reserves Bureau (SRB) is at the centre of industry talk that a dealer working on its behalf had taken out a 150,000 to 200,000 tonne bet that copper prices would fall, only for the market to hit new record highs.
"The funds are massively long, and so long as they don't get any sell signals, there is no reason for them to let go. In the meantime, they are just adding small lots," another dealer said.
Prices have jumped as investors have tested public comments by the SRB that it will intervene by selling up to 500,000 tonnes of its reported 1.3-million stocks to cool prices.
But LME stocks, at just 64,350 tonnes, are insufficient to meet commitments against the short positions and it is unlikely that metal can be delivered and warranted in time, dealers said.
Aluminium was back up after dropping in the past two days after large LME stock increases.
Three-month was at $2,037, from $2,008, while lead, which rose above $1,000 on Thursday, was at $995, up $10.
Zinc reached a fresh eight-year high of $1,650, ending the rings at $1,646, up from a previous $1,626.
Nickel was at $12,350, versus $11,950, while tin was at $6,000, from $6,105.