Video report by ITV News Correspondent Juliet Bremner
Charities and NGOs will face greater government scrutiny, the international development secretary has vowed, following allegations of sexual misconduct by aid workers.
It comes as the Charity Commission prepares to launch a statutory inquiry into Oxfam and the charity's deputy chief executive resigned over claims its employees sexually exploited victims of the 2010 Haitian earthquake and hired prostitutes for sex at homes funded by the charity in Chad in 2006.
International Development Secretary Penny Mordaunt said her department would set up a dedicated unit to "urgently review safeguarding across all parts of the aid sector".
That could include setting up a global register of aid workers in order to "guard against criminal and predatory individuals being re-employed by charities and abusing again".
While Oxfam investigated the allegations of misconduct in 2011 and told DfID it had dismissed a number of its employees, it failed to report the allegations were about sexual misconduct towards the charity's beneficiaries.
Now it faces an inquiry by the Charity Commission over concerns it may not have "fully and frankly disclosed" all the details of the allegations in Haiti.
The Oxfam revelations led to a threat over the weekend that the government could withdraw its funding to what is one of Britain's largest charities.
There was no sign of that following a meeting between Ms Mordaunt and Mark Goldring, Oxfam's CEO on Monday.
Instead Ms Mordaunt demanded assurances that Oxfam would step up their procedures for dealing with allegations of misconduct, saying that the charity would be judged "on the basis of their actions going forward".
She said Oxfam had given "a full and unqualified apology – to me, and to the people of Britain and Haiti" for the actions of their employees.
Earlier the charity's deputy chief executive Penny Lawrence stepped down saying she took "full responsibility" for the behaviour of its staff in Chad and Haiti.
In a statement Ms Lawrence she said: "I am desperately sorry for the harm and distress that this [misconduct] has caused to Oxfam's supporters, the wider development sector and most of all the vulnerable people who trusted us."
Mr Goldring said: "I deeply respect Penny's decision to accept personal responsibility. Like us, she is appalled at what happened and is determined to do what is best for Oxfam and the people we exist to help."
In an interview with ITV News on Saturday he denied Oxfam had lied to the government in 2011 over sex claims about its workers.
"I don't think Oxfam deliberately lied," he told ITV News. "I fully recognise that by telling half a story it feels that way. And with hindsight we should have told the whole story."
At the centre of the Oxfam claims is Roland van Hauwermeiren, who was the charity's country director in Haiti.
He admitted during an internal investigation that he paid women for sex and later resigned, along with two other senior members of staff. Four others were dismissed.
An internal report by the charity noted it could not categorically rule out that the prostitutes had been underage.
Haiti has since demanded those accused in the scandal be identified.
Haiti's ambassador to the UK, Bocchit Edmond said there was a "culture of cover up".
"That crime should never have been committed," he said.
"Your mission was not to exploit, to sexually exploit those girls, your mission was not to go to solicit prostitutes, your mission was to go and help those people in need, not to use your power and advantage to exploit them."
Video report by ITV News Correspondent Paul Davies
Now the spotlight is being shone on other charities, with Save the Children, Christian Aid and the British Red Cross all confirming they have dealt with cases of sexual abuse or harassment by staff in the past 12 months.
Charity Commission director of investigations Michelle Russell said about 1,000 incidents a year are reported to the watchdog and that the charity sector is "not immune" from incidents involving safeguarding issues.
She told ITV News: "Any, even if it is one incident is shocking and appalling. But it is not of a surprise in some respects that there are more allegations coming out now because the charity sector is not immune from this. We've seen this in other parts of society, in other sectors.
"We're trying to say to charities, be transparent and accountable about this."
Ahead of its meeting with the international development secretary, Oxfam announced a package of measures to improve safeguarding, including improved recruitment and vetting and a new whistleblowing helpline.
Caroline Thomson, Oxfam's chairwoman of trustees in the UK, said: "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."
She added that concerns raised about the recruitment and vetting of staff involved in the scandal were being examined.