Harare - The international campaign group Global Witness on Wednesday queried the credibility of a report by a diamond monitor which said Zimbabwe had met standards to resume trade in the gems.
"There is no sign that state-sponsored brutality in the diamond fields has stopped or that the widespread smuggling of diamonds from Marange into neighbouring countries has been curbed," Global Witness said in a statement.
"Lifting the ban on Marange exports would mean letting blood diamonds onto international markets.
"Global Witness has serious concerns about the credibility of the report, which recommends that Zimbabwe be allowed to resume diamond exports from the controversial Marange area."
The statement came after a report from the diamond monitor Kimberley Process (KP) said Zimbabwe had "satisfied minimum requirements of Kimberley Process certification scheme or trade in rough diamonds."
The report followed the arrest on June 3 of Farai Maguwu, head of the Marange-based Centre for Research and Development, after a meeting with the KP monitor Abbey Chikane.
The organisation regularly provided information about abuses in Marange to the Kimberley Process.
A magistrate in Harare was to make a ruling on Wednesday whether Maguwu, who was accused of publishing information that would jeopardise the economic interests of the country, should be prosecuted.
The International Centre for Transitional Justice said Maguwu's arrest would taint the country's power-sharing government.
"Arresting Maguwu is like shooting the messenger," the group said.
"If the inclusive government is to have any credibility, it must cease this kind of harassment," it said in reference to an uneasy national unity government.
Last year Kimberley Processes investigators documented forced labour, beatings and other abuses by the military against civilians in the eastern Marange diamond fields.
Zimbabwe had faced a June deadline to end human rights abuses at Marange and Chikane was appointed KP's monitor to Harare to ensure compliance.