China's refined copper surplus is expected to widen in 2014, on lower demand from the collateralized borrowing sector, as well as a slowdown in the domestic private sector's construction activities, Chinese industry experts said Thursday.

"Although the infrastructure sector is expected to enjoy stable growth this year due to support from the government, demand from the collateralized borrowing sector and private sector construction industry has slowed down," Jack Yeung, a business professor with City University of Hong Kong said.

"August is the traditional low copper consumption season in China. We don't expect a considerable pickup in demand, even when the boom buying season arrives by October ... which would cause the higher surplus this year," he added.

State-owned nonferrous metals information division Beijing Antaike had forecast a surplus of 1.18 million mt, up from 730,000 mt last year, in its half-year copper commodities report issued in end-July.

Antaike said funds' enthusiasm in the copper market this year has been weaker compared with the aluminum, zinc and nickel markets, given lower opportunities for speculative trading.

Meanwhile, Antaike expects China's refined copper output to hit 6.83 million mt in 2014, up 7% from 2013. Copper consumption this year is forecast at 8.75 million mt, up 6.7% from 2013.