LONDON » Britain has urged the authorities in Zimbabwe to investigate a BBC report that its security forces are beating and raping prisoners at two camps in the Marange diamond fields in the east of the country. International monitors voted to allow exports from the fields to resume in June despite objections from the United States, Canada and the European Union.

On Monday, the BBC’s documentary program "Panorama," said the camps hold workers who were recruited by the police and the military to dig illegally for diamonds for them, but who then demand too large a share of the profits. The camps also hold civilians who have been caught mining for themselves, the program said.

According to the report, a released prisoner who was not named said guards at the camps were beating prisoners three times a day, with 40 lashes at a time. Dogs were loosed to bite shackled prisoners, and women held at the camps were frequently raped, the program said.

The Zimbabwean authorities offered no immediate comment.

The government of President Robert Mugabe has been working to increase its legal sales of diamonds. Mugabe’s political opponents fear that he will use diamond income to finance a violent campaign to win elections that are likely to be held next year.

One of the torture camps identified, called Diamond Base, is about a mile from the Mbada mine, which the BBC says is run by a friend of Mugabe. Witnesses cited by the program described Diamond Base as "a remote collection of military tents, with an outdoor razor wire enclosure" to hold the prisoners.

The network said a European Union document showed that the union was ready to accept the June decision to allow exports from two Marange mines, including the Mbada mine, a move made by the Kimberley Process, a global body set up almost a decade ago to halt the sale of so-called blood diamonds.

In a statement Monday, Britain’s minister for Africa, Henry Bellingham, said his country supported exports from two Marange mines that met Kimberley standards, "subject to ongoing monitoring." One is the Mbada mine, the BBC reported.

The Marange fields were discovered in 2006 and violently taken over by Zimbabwe’s military in 2008. Bellingham’s statement called that the takeover of the fields was "a harrowing and brutal chapter."

"We utterly condemn all extrajudicial killings and call on the Zimbabwean authorities to transparently investigate both the dreadful events of 2008," he said in a statement, as well as "the disturbing allegations" in the BBC documentary.

"The UK is absolutely committed to eradicating the trade of conflict diamonds," the statement said, noting that Britain "played a leading role" in creating the Kimberley Process.

The group embraces governments, the diamond industry and advocacy groups. A year ago, it allowed limited sales from the Marange fields to resume; its decision in June to expanded export rights raised questions because of the deep Western objections. Decisions by the body are supposed to be taken with broad consensus.

The charter of the Kimberley Process, initially intended to halt diamond sales that were used to finance rebel groups, does not specifically address diamond sales used by an army or a government to commit human rights abuses.

The struggle over the Marange mines has thrown the monitoring group into disarray, leaving Western governments and advocacy groups pitted against Zimbabwe’s African allies.

Some advocacy groups walked out of the meeting in June that authorized Marange sales, protesting the Kimberley Process’ "failure to address human rights abuses associated with the diamond trade" and complaining that the organization did not have the political will to enforce its own vaunted standards.