Shanghai Futures Exchange copper closed up 1 percent at 36,270 yuan ($5,512) a tonne but gains were capped as Britain geared up to vote on whether to leave the European Union. China's domestic copper market tightened in early June, as surplus metal was moved into international storage. But domestic supply appears to be improving, with premiums for metal for immediate delivery - as seen in front month ShFE futures against further dated contracts - last at nearly flat from as high as 200 yuan at mid-month.
Suggesting there is still appetite for imports, however, premiums for shipments to China on a cost, insurance and freight basis firmed by $2.50 to $40-$60, up from as low as $35 mid-month, which was the weakest in four years. In news, China's debt defaults will not pose a systemic risk as long as economic growth remains within a reasonable range, according to a government document on Thursday. The International Monetary Fund said on Wednesday the US economy was "overall in good shape," with growth set to regain momentum despite an overvalued dollar.