End users in China, the world's top consumer and producer of refined copper, typically increase purchases around the second quarter to support higher production as the summer approaches.
But this year, many have been reluctant to build copper stocks and have been buying hand-to-mouth, according to traders.
Weaker than expected Chinese demand could drag on international copper prices, which have risen more than 10 percent from the multi-year lows hit in January. They stood at $6,036 a tonne on Thursday.
"Even now Chinese end users are buying what they need for immediate production. They don't see prices rising strongly in the near term," said a Shanghai-based trader at an international trading firm. He declined to be identified as he was not authorised to talk to media.
Chinese banks have also reduced lending to metals firms after an alleged metal financing scam at the port of Qingdao came to light in June 2014.
Reflecting weak import demand, premiums for bonded stocks of refined copper in Shanghai have eased to $60-$90 a tonne over the cash LME copper prices this week, from about $90 in early March.
While metals firms are receiving fewer loans from banks, many sellers of refined copper and semi-finished copper products such as rods require buyers to pay cash on delivery, piling pressure on end users, traders said.
"Factories appear very short of cash. But many sellers have asked for cash this year, different from the two-week payment period in previous years, after some clients defaulted on payments last year," said a Guangdong-based trader at a large maker of copper rods, used for manufacturing electricity cables and wires.