Further purchases by China's State Reserves Bureau (SRB) could help absorb the small surplus forecast to weigh on the global refined copper market this year and help support prices that have already dropped nearly 10 percent so far this year.

Two of the sources said State Reserves Bureau was considering bringing forward its 2015 stockpiling plan due to the current low copper prices.

Every year we hear of the dreaded surplus and then something happens and it drifts away. Here again they refer to the "small surplus forecast" so it is already down from the huge one that has hit pricing. If they bring forward their 2015 purchases there won't be a surplus at all, especially since anything else could happen to production and tip the balance.

If they are thinking of bringing it forward from 2015 it is because they think the prices will be more favourable this year than next. That's why they are stockpiling now.