JOHANNESBURG — An international body charged with stopping the illicit trade in diamonds that fuel conflict has decided not to suspend Zimbabwe, officials said Friday, though its investigators had concluded Zimbabwe's military had organized smuggling syndicates with the government's permission and used "extreme violence" against illegal miners.

Instead, the countries who are part of the U.N.-endorsed Kimberley Process decided to send a monitor to decide whether future exports of rough diamonds from the troubled Marange fields in eastern Zimbabwe can be certified as conflict-free.

Human rights campaigners and nongovernmental organizations immediately denounced the decision, saying the body had showed it was incapable of stopping gross abuses and the flouting of international standards.

Bernhard Esau, the Namibian deputy mining minister who heads the Kimberley Process, said in an interview on Friday that the nations who belong to the body had listened to what Zimbabwe "told us as a Kimberley family" and decided to give the government a chance to come into compliance with international standards.

"If that time comes, we'll have to see if those things have been met or not," he said. "I am hopeful, but I don't want to be let down. I'm giving them the benefit of the doubt."

The plan agreed to on Thursday calls for private security companies, Zimbabwe's police force and its mining ministry to secure the fields, while the military withdraws in phases.

Zimbabwe's mining ministry, as well as the police and military forces, are under the control of President Robert Mugabe and his ZANU-PF party, though he is now in a power-sharing government with Prime Minister Morgan Tsvangirai and his Movement for Democratic Change.

Zimbabwe's mining minister, Obert Mpofu, told the Kimberley gathering, held this week in Swakopmund, Namibia, that the situation in the Marange fields was improving. Zimbabwe's state-run newspaper, The Herald, this week described the effort to stop the trade in Zimbabwe's diamonds as being led by Western nations and based on "a glut of unsubstantiated claims of human rights abuses."

Critics said the decision demonstrated the ineffectiveness of the process set up to police the international diamond trade.

"This failure to act has sent a bad message," said Annie Dunnebacke of Global Witness, an organization that has advocated strict controls on diamond production. "It says if you don't follow the rules, there will be no serious consequences."