THE European Union offered Thursday to help Zimbabwe address mounting concerns over graft in its diamond sector, only months after the industry watchdog lifted a ban on sales.

The EU head of mission in Harare told AFP after leading the first visit by a group of Western diplomats to the eastern Marange mines that the bloc could help Zimbabwe set up inspection mechanisms that meet international standards.

"We note that there is a problem of transparency in the diamond mining sector's revenues, which is reflected in the positions that the Zimbabwe minister of finance has expressed publicly," Aldo Dell'Ariccia said.

Concern over Zimbabwe's diamond mines has swung from a global outcry over a state-sponsored purge of artisanal diggers to questions about the trail of profits from the deposits which are now formally mined for the global gem trade.

Finance Minister Tendai Biti has complained about lack of information on revenue from the diamond sector, raising suspicions that some of the funds are bypassing central government coffers.

"Transparency is a political issue but it is also a technical issue, that demands proper capacity to carry out due inspections," said Dell'Ariccia.

"Therefore, if so requested by the government of Zimbabwe, the EU could provide the necessary technical assistance to update, upgrade, complete the national installed capacity to carry out proper inspections," he said.

The EU envoy led a team of ambassadors from Australia, Belgium, Canada, Czech Republic, Denmark, France, Germany and Spain on the diamond mines tour which he said was a fact-finding mission at the invitation of the Zimbabwe government.

He described management at one of the firms Western diplomats visited as "excellent, really international standards" and said that the security standards of the anti-conflict body, the Kimberley Process, were "respected".

Zimbabwe had expected to rake in $600 million from diamond sales this year, after the global watchdog in November lifted a ban that was imposed over military abuses in the fields, including Marange.

But in the first quarter of 2012, only about a quarter of the projected diamond revenue for that period was received, according to Biti.

Anjin, a company jointly owned by the government and a Chinese firm, and also the largest of the four diamond mining companies in the country, had failed to remit its revenue to the central government, Biti said.

But an Anjin director told the diplomats on Tuesday that a payment of $30 million had been made to government in royalties.

Biti has suggested that "there might be a parallel government somewhere in respect of where these revenues are going."

The army cleared small-scale miners from the area in 2008 in an operation that Human Rights Watch says killed more than 200 people.

The EU chief said there had been no major rights incidents there lately.

A policeman is on trial for the kidnapping of four villagers, one of whom later died.

The fact a trial is under way "is something that demonstrates that there is a certain change in the reality."