HARARE, June 13 (Reuters) - Zimbabwe's government will soon lift its ban on diamond exports and expects to trade more than 4 million carats from the controversial Marange fields, state media reported on Sunday.

Mines minister Obert Mpofu, last month stopped all diamond exports, including from Rio Tinto's (RIO.AX: Quote) (RIO.L: Quote) Murowa mines and the privately owned River Ranch, until stones from the government's Marange fields were certified by industry regulators.

Last week, a monitor appointed by the Kimberley Process Certification Scheme (KPCS) to assess the government's mining operations at Marange said Zimbabwe had met the minimum conditions set by the industry regulator and could start gem exports.

The state-controlled Sunday Mail newspaper quoted Mpofu saying Zimbabwe would now lift the diamond export ban and begin the auction of its own gem stockpile of 4 million carats, which the paper said could be worth up to $1.7 billion.

"We have met the criteria and what is now left is to start exporting the diamonds," Mpofu is quoted saying.