(AFP) - Oxfam announced a new raft of measures to tackle sexual abuse cases after being ordered to meet the British government on Monday to explain its handling of a 2011 prostitution scandal involving its aid workers in Haiti.

The British-based charity will reexamine the episode as part of an independent review started this year to drive out unacceptable behaviour, while pledging to improving the recruitment, vetting and management of staff.

"It is not sufficient to be appalled by the behaviour of our former staff -- we must and will learn from it and use it as a spur to improvement," Caroline Thomson, Oxfam's chair of trustees, said in a statement.

She confirmed the charity would meet with the Department for International Development (DFID) on Monday and the Charity Commission, which regulates the sector, later this week.

Earlier Sunday Britain's International Development Secretary Penny Mordaunt warned Oxfam to cooperate with a renewed probe into the scandal or face repercussions.

"If they do not hand over all the information that they have from their investigation... then I cannot work with them any more as an aid delivery partner -- and any other organisation in those circumstances," she told the BBC.

- Widening fallout -

In a sign of widening fallout, the Sunday Times reported more than 120 workers for Britain's leading charities were accused of sexual abuse in the past year, "fuelling fears paedophiles are targeting overseas aid organisations".

Mordaunt said she was writing to all charities that receive state aid demanding they step up efforts to tackle sexual misconduct among staff or face funding cut-offs.

She will also seek to confirm they have referred all concerns about specific cases and individuals to the relevant authorities.

"I think this is an emerging picture, there are more allegations coming out about Oxfam and other organisations... and all of them will be followed up," Mordaunt vowed.

The government's hardening stance follows reports in The Times newspaper that young sex workers were hired by Oxfam's senior staff in Haiti after the 2010 earthquake which devastated the island and left up to 300,000 people dead.

The charity -- which employs around 5,000 staff and has 23,000 more volunteers -- also recorded 87 sexual abuse incidents last year, referring 53 to the police or authorities and dismissing 20 staff or volunteers, according to the Sunday Times.

Oxfam Chief Executive Mark Goldring admitted Saturday that it had failed to detail fully the nature of the 2011 scandal but insisted it "did anything but cover it up".

"With hindsight, I would much prefer that we had talked about (the) sexual misconduct," Goldring told BBC radio.

"But I don't think it was in anyone's best interest to be describing the details of the behaviour in a way that was actually going to draw extreme attention to it."

- Moral leadership -

However, Mordaunt said not disclosing the full picture was "a scandal" and Monday's meeting was a chance "to see if they are displaying the moral leadership that I think they need to now".

She added: "what is so disturbing about Oxfam is that when this was reported to them, they completely failed to do the right thing."

The minister noted offences committed by British citizens anywhere in the world could still be prosecuted in Britain.

"We're talking about a historic case, but it is in some respects still live.

"They still have information they should be giving to the authorities."

Oxfam has said it launched an immediate investigation in 2011 which found a "culture of impunity" among some staff.

During the probe, it dismissed four staff members and another three resigned.

The charity has also said it had yet to find evidence proving allegations that underage girls were involved.

© Agence France-Presse