The ready availability of refined copper is weighing on Chinese prices, while strong international prices have weakened China's demand for spot imports, traders said on Thursday.

Production in China, the world's top consumer of the metal, may reach an average of 330,000-350,000 tonnes a month this year versus monthly output of 286,783 tonnes last year, traders estimated.

This year's monthly output would rise because of smelters' expanded capacity despite output being hurt by snow-related power shortages and logistics problems in January and February.

"Chinese prices have lagged behind international prices due to few factors -- steady imports, high local output and high stocks," a manager at an investment firm in Shanghai said.

"We will not buy copper until we see good premiums on physical copper," the manager said.

Benchmark three-month London Metal Exchange copper prices have risen 31 percent this year to $8,715 a tonne on Thursday, not far from the peak of $8,820 seen in March.

But the third month contract of the Shanghai Futures Exchange, June , has risen 17 percent this year to 66,320 yuan ($9,487) a tonne on Thursday.

China's March arrivals of refined copper may have surpassed February's 136,243 tonnes as merchants had placed large amounts of spot orders in January-February.

Some imports were stored in bonded warehouses in Shanghai since Chinese prices have stayed low in the past two weeks, traders said.

They estimated bonded stocks rose to 60,000-70,000 tonnes, versus 40,000-50,000 tonnes a month ago.

Copper stocks in the exchange's warehouses rose 4.7 percent, or 2,588 tonnes to 58,195 tonnes last week, while traders said stocks might rise further by about 4,000 tonnes this week. The latest data will be released on Friday.

"Imports in April should fall from March on lower spot arrivals," a manager at one large trading house said.

He said importers were seeking to resell term imports due to arrive in late April to early May at low premiums of $20-$30 a tonne over cash LME prices , against premiums of $90-$110 they had paid to overseas suppliers.

Costs of importing the metal were more than 5,000 yuan ($715) a tonne higher than Chinese spot prices, traders said.

A trader at Baiyin Nonferrous said the firm on Thursday had sold copper for prompt delivery at discounts of 150 yuan a tonne from the price of the nearest Shanghai copper contract, April , which ended at 65,830 yuan a tonne on the day.

Beijing's tight credit policy was also hurting demand as that had reduced end-users' cash for building copper stocks, traders said.

"Demand is not as good as many had expected. People had expected after-snow rebuilding to boost copper demand, but that has not been happening," a futures dealer for a large trading firm in Shanghai said.

A manager at Baosheng Science <600973.SS>, a power cable maker, said the rebuilding was increasing demand for aluminium-based overhead power cables and was unlikely to benefit copper-based underground power cables.

($1=6.9905 yuan)