VICTORIA FALLS, Zimbabwe — At least $2 billion worth of diamonds have been stolen from Zimbabwe’s eastern diamond fields and have enriched President Robert Mugabe’s ruling circle, international gem dealers and criminals, according to an organization leading the campaign against conflict diamonds.

Zimbabwe’s Marange fields have seen “the biggest plunder of diamonds since Cecil Rhodes,” the colonial magnate who exploited South Africa’s Kimberley diamonds a century ago, charged Partnership Africa Canada, a member of the Kimberley Process, the world regulatory body on the diamond trade.

Zimbabwe’s eastern Marange field — one of the world’s biggest diamond deposits — has been mined since 2006 and its vast earnings could have turned around Zimbabwe’s economy, battered by years of meltdown and political turmoil, the group said. But funds from the diamond sales have not shown up in the state treasury. Instead there is evidence that millions have gone to Mugabe’s cronies.

The report, released Monday to coincide with the Zimbabwe government’s conference on the diamond trade here in Victoria Falls, casts a shadow over the Mugabe regime’s effort to win international respectability for its gem trade. Government officials at the conference denied the report’s allegations as “totally false.”

Mugabe pledged that Zimbabwe will soon have new law to ensure greater transparency and accountability in order to boost the “international reputation of our diamonds.” Opening the conference, Mugabe said his government is committed to observing “international laws on diamond mining, storage and trading.”

The report condemns the Mugabe government’s control of the Marange diamond fields, which have made Zimbabwe a major player in the international diamond trade.

“Marange’s potential has been overshadowed by violence, smuggling, corruption and most of all, lost opportunity,” the Partnership Africa Canada report said.

“The scale of illegality is mind-blowing,” the report said.

The report describes the $2 billion lost to the Zimbabwe treasury as a “conservative estimate.”

Finance Minister Tendai Biti said in his 2012 budget that he had been promised $600 million in diamond revenue for the national treasury to help refinance crumbling health, education and other public services. Biti said that only one-fourth of that pledge has been received.

Mines Minister Obert Mpofu, a Mugabe loyalist, insists that Western economic sanctions have prevented the government from getting good prices for the diamonds on the international market. But Mpofu has repeatedly refused to give exact figures on diamond revenue, said the Partnership Africa Canada report.

Mpofu, the mines minister since 2009, amassed an unexplained personal fortune and is linked to a “small and tight group of political and military elites who have been in charge of Marange from the very beginning” and who are personally benefiting from the diamond sales, the report alleged.

In 2010 leading industry insiders, including Filip van Loere, a Belgian diamond expert working for the Mugabe government, forecast the country could produce as much as 30 million to 40 million carats a year, worth about $2 billion annually, the Partnership Africa Canada report said. The diamonds are being mined and sold, but the funds are not reaching the Zimbabwean treasury, according to the report.

Most of the diamond revenue is lost through a lack of transparency in accounting for how many diamonds are mined, how much is earned from their sales, the underpricing of gems on world markets, smuggling and a “high level of collusion” by government officials.

Records show that 10 million carats of Marange diamonds were exported to Dubai in late 2012 for $600 million, which the report said is an artificially low price because the same stones were sold for double their original price when they left Dubai for Surat, India — the world’s biggest diamond cutting center. It says the gems should have been valued at $1.2 billion.

In addition, the report’s researchers were unable to locate a 2.5 million carat stockpile, valued at about $200 million, which mysteriously disappeared in November 2011. It also charges that $300 million in diamond sales never made it to the Zimbabwe treasury in 2011.

Business, Pages 32 on 11/14/2012