The National Crime Agency is “closely monitoring” allegations of abuse by Oxfam staff and other aid agencies amid government warnings about public funding.

Sexual offences committed outside the UK can be investigated by the agency, which is to meet with the International Development Secretary on how to support foreign police forces.

The agency said it would work with the Government to protect potential victims abroad and present recommendations on what more should be done.

“We are meeting with the Charity Commission this week to assure ourselves that appropriate action has been taken with all the safeguarding material in their possession and to improve standards,” a spokesperson for the agency said.

The commission, which has been forced to defend its own investigations into Oxfam after a whistleblower reported that women were being coerced into sex for aid, held an all-day meeting with the charity after opening a new statutory inquiry.

Details of the probe, covering allegations which include that Oxfam did not “fully and frankly disclose material details” about staff using prostitutes in Haiti in 2011, are to be published on Thursday.

The Government has warned that aid agencies failing to offer adequate assurances about their safeguarding processes and transparency could have funding withdrawn, while Labour is calling for a full inquiry.

Kate Osamor MP, the shadow International Development Secretary, said officials must “uncover how prevalent abuse is, how it is happening and what we can do to stop it”.

“What happened within Oxfam is absolutely inexcusable, and to make matters worse we do not yet understand just how widespread the abuse is,” she wrote in The Independent.

“Some have, disgracefully, weaponised this appalling scandal by launching a full-frontal assault on UK aid.

“But there is no moral defence for cutting aid that helps millions of people in extreme poverty and those facing conflict and persecution, and saves hundreds of thousands of women and girls from sexual violence.”

Penny Mordaunt, the International Development Secretary, indicated that the £31.7m the Government awarded to Oxfam last year, and its financial support for other charities, could be cut off unless changes are made.

“I will be guided in my decisions about Oxfam depending on the charity’s response to questions I have raised with them, and by the Charity Commission’s investigation,” she told an aid conference in Stockholm

“No organisation is too big, or our work with them too complex, for me to hesitate to remove funding from them if we cannot trust them to put the beneficiaries of aid first.

“The recent revelations about Oxfam – not solely the actions perpetrated by a number of those staff, but the way the organisation responded to those events – should be a wake-up call to the sector.

“They let perpetrators go. They did not inform donors, their regulator or prosecuting authorities.

“It was not just the processes and procedures of that organisation that were lacking, but moral leadership.”

Ms Mordaunt said that while any potential criminals must be prosecuted, the “culture that allowed this to happen needs to change”.  

Hollywood star Minnie Driver became the first celebrity to quit as an Oxfam ambassador amid wavering support from sponsors including the Duke of Edinburgh’s Award.

Marks & Spencer, Visa and Heathrow Airport were also among the organisations which said they were reviewing lucrative partnerships with Oxfam. 

The scandal has already caused the resignation of the charity’s deputy chief executive Penny Lawrence, who said she took “full responsibility” for the alleged use of prostitutes by senior staff in Haiti and on a previous placement in Chad.

Four members of Oxfam staff were dismissed, and three, including the country director Roland van Hauwermeiren, resigned before the end of an internal investigation in 2011.

While working for another charity, Mr Van Hauwermeiren allegedly used donor-funded drivers to ferry him to meet prostitutes in Liberia in 2004.

Complaints from colleagues caused him to leave, but he was able to start working for Oxfam two years later.

The charity has issued an “unreserved apology” to the Government, donors, supporters and the people of Haiti about its handling of the allegations.

Pressure has increased on its chief executive Mark Goldring to resign following calls from critics including the former International Development Secretary Priti Patel, but he said he would only leave his job if asked to by the board.

Oxfam International chairman Dr Juan Alberto Fuentes Knight stepped down on Wednesday after being arrested in an unrelated corruption probe linked to his work as a government minister in Guatemala.

The charity said it supported “his decision to devote his time now to vigorously contest these charges”.

The Government has written to all British charities working overseas demanding “absolute assurances” that they are protecting vulnerable people and referring complaints to authorities.

A new unit dedicated to reviewing safeguarding in the aid sector and stopping “criminal and predatory individuals” being employed by other charities has been created, and a global register of development workers may be established.

Existing schemes include the voluntary International Child Protection Certificate, which attempts to help protect children from British nationals who seek to work overseas in order to abuse them and saw more than 11,000 applications in 2016/17.