Video report by ITV News Correspondent Paul Davies
Haiti's President Jovenel Moise has slammed charity Oxfam describing the alleged sexual misconduct of aid workers in the country as a "serious violation of human dignity."
The charity has issued an "unreserved apology" to the Government, donors, supporters and the people of Haiti over its handling of incidents including the alleged use of prostitutes by workers, in the earthquake-hit country in 2011.
The President said: "What happened is an extremely serious violation of human dignity.
"This case is all the more odious because the funds which financed these crimes were obtained from the British people in a spirit of altruism and solidarity towards the Haitian people."
He added: "Let it be clear to all of Haiti's international partners, if their personnel exploit or do wrong to our citizens when they are supposed to be 'aiding' them, we will not be inclined to tolerate it and we will not tolerate it."
The aid charity's leaders in Haiti are expected to be called in for crisis talks with Mr Moise's government as it considers its response.
Video report by ITV News Correspondent Martha Fairlie
Haitian charity worker Romel Jean Pierre told ITV News overseas aid workers are still taking advantage of people on the island.
"If I go out with you tonight, going to a few places, you'll realise there's a few men in khakis, like you know directly they are aid workers, surrounded by young Haitian girls," he said.
"So for me it's (exploitation) is not surprising because it's well-known now, everyone knows about it, but no one is speaking about it."
There are also fresh accusations against Roland van Hauwermeiren, Oxfam's head of staff during the Haiti crisis, who resigned in 2011 after allegations he and other said workers paid local prostitutes for sex.
It has now been claimed he was forced to leave charity Merlin seven years earlier for similar reasons.
The accusation was made by a female worker, who said she reported him to the charity.
International Development Secretary Penny Mordaunt said she took the allegations raised against Oxfam "very seriously" but said decisions over funding for the charity "should not be taken hastily".
She made the comments after a former Oxfam employee said she encountered allegations of rape, harassment and sex in exchange for aid handouts when she was working for the charity.
Ms Mordaunt said: "I'm going to take these things very seriously. I know people will be worried about the charity, worried about the money but we need to be guided by what the Charity Commission are doing.
"Also, I have made it very clear to Oxfam what we expect to see from them but these decisions shouldn't be taken hastily but I'm considering them."
The charity received £31.7 million from the UK Government in 2016/17, but the support has been put at risk by the scandal.
The charity has been given until the end of the week to explain how it will handle further allegations.
Chief Executive Mark Goldring said that he had no intention of resigning, after his deputy stepped down on Monday.
He added: "However, if the board were to turn round and say you're not the right person to lead Oxfam forward, then of course I would fully respect that."
In an interview with Channel 4 News the former head of global safeguarding at Oxfam, Helen Evans, said during her time with the charity she was told about two women being coerced to have sex and a worker who had failed to disclose he had previously been struck off for sex abuse.
She said she begged senior staff, ministers and the regulator to act on the sexual abuse allegations.
"There was a woman being coerced to have sex in a humanitarian response by another aid worker," she said.
"[There was] another case where a woman had been coerced to have sex in exchange for aid and another one where it had come to our attention that a member of staff had been struck off for sexual abuse and hadn't disclosed that, and we were then concerned about what he might be doing," she added.
Ms Evans revealed that she told the charity that there was a need for more resources to tackle the number of allegations.
It comes as the Charity Commission prepares to launch a statutory inquiry into Oxfam amid concerns Oxfam may not have "fully and frankly disclosed material details" when it first investigated allegations of misconduct in 2011.
The charity's deputy chief executive, Penny Lawrence, resigned on Monday 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.
Upon her resignation Ms Lawrence said she took "full responsibility" for the behaviour of its staff in Chad and Haiti.
In a statement 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."
Responding to her resignation, 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.
The Department for International Development is to 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 the Department for International Development 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.
Shadow international development secretary Kate Osamor said: "The Charity Commission and Government departments have serious questions to answer: Why did they take no action in response to concerns raised by Helen Evans in June 2015 and August 2015? Are there other whistleblowers that have brought safeguarding concerns to the Charity Commission only to be ignored?
"It is crucial that we now understand how far this appalling scandal reaches, and whether the Charity Commission is operating effectively as an independent regulator."
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.