The British government is reviewing its relationship with Oxfam amid a deepening sexual misconduct scandal involving some of the charity's employees working in Haiti after its devastating 2010 earthquake.

The United Kingdom's Department for International Development sharply criticized the charity for its lack of transparency as questions swirled about how much detail Oxfam provided when it first reported the allegations. The agency, which gave £31.7 million ($55.2 million Cdn) to Oxfam last year, demanded that Oxfam's senior officials meet with it to explain their actions.

"If wrongdoing, abuse, fraud or criminal activity occur, we need to know about it immediately, in full," the agency said. "The way this appalling abuse of vulnerable people was dealt with raises serious questions that Oxfam must answer."

The Times of London reported Friday that misconduct allegations against seven former Oxfam staff in Haiti included the use of prostitutes — some of whom may have been under 18 — and downloading pornography. It said Oxfam's investigation into the charges was hampered by a "determination to keep it out of the public eye."

Oxfam said it investigated the allegations in 2011. The charity confirmed it had dismissed four people and allowed three others to resign in the case after an investigation uncovered offences including sexual misconduct, bullying, intimidation and failure to protect staff.

The charity said it had reported the results of its investigation to Britain's charity regulator and to major donors, including the Department for International Development.

The charity commission demanded further information from Oxfam on Saturday, saying it had "made no mention of any potential sexual crimes involving minors," when it first reported the investigation in 2011.

"Our approach to this matter would have been different had the full details that have been reported been disclosed to us," the commission said.

Oxfam said Friday the behaviour in Haiti was "totally unacceptable, contrary to our values and the high standards we expect of our staff."

On Saturday, Oxfam was forced to deny further reports that it gave positive references to those it dismissed.

"Oxfam has not and would not provide a positive reference for any of those that were dismissed or resigned as a result of the case," the charity said.

Oxfam said some former workers may have falsified references or asked individual staff members to provide references, but said it couldn't prevent such actions.