The survey of 10 economists showed the landlocked southern Africa nation's economy expanding 6.8 percent this year, slightly below the 6.9 percent forecast in a June poll, and then by 7.1 percent in 2013.

While better than an estimated 6.6 percent growth for 2011, that would still be some way short of the 7.6 percent rise in gross domestic product (GDP) in 2010 that was mainly driven by the construction sector.

Foreign mining companies are increasingly investing in Zambia, and the resulting windfall will give a boost to other industries too.

"GDP growth in Zambia is expected to be driven by strong growth in agriculture, the mining sector and construction," said Fredrick Mulenga of Zanaco, a state-owned bank.

The slight downgrade from the previous consensus can be attributed to a sharp fall in copper production during the first half of this year, as orders waned from resource-hungry China.

Nonetheless, growth in Zambia is still up there with other heavyweights in the continent.

The government has targeted growth of 8 percent over the next five years and for the inflation rate to stabilise to 5 percent over the medium term.