U.S. gem group bans Zimbabwe's Marange diamonds

HARARE, Aug 16 (Reuters) - A leading diamond trading network has barred its members from dealing in stones from Zimbabwe's Marange fields, saying their certification by global regulators did not guarantee they were free from human rights abuses.

The Kimberley Process (KP) certification scheme, set up to keep "blood diamonds" -- stones from conflict zones -- out of global gem trade, last week endorsed the sale of 900,000 carats fron Zimbabwe's controversial Marange fields.

Human rights activists have called for a ban on diamonds from Marange, where Zimbabwe's army is accused of widespread atrocities when it moved in to guard the poorly secured fields after a diamond rush drew up to 30,000 illegal diggers.

The United States-based Rapaport Diamond Trading Network said although the Marange diamonds had received KP endorsement, it will not allow its members to trade in them.

"Members found to have knowingly offered Marange diamonds for sale on RapNet will be expelled and their names will be publicly communicated," it said in a statement.

Zimbabwe, which denies rights abuses at the Marange fields, says it has stockpiled nearly 4 million carats of diamonds since the start of the year, estimated by state media to be worth $1.7 billion.

A power-sharing government formed by President Robert Mugabe and Prime Minister Morgan Tsvangirai last year in a bid to end a decade-long political and economic crisis has said it hopes diamond revenues can help fix the struggling economy.

Reporting by Nelson Banya, Editing by Ed Cropley