A number of Oxfam’s corporate partners have said they are looking closely at how the charity has responded to the sex scandal.

Marks & Spencer, Heathrow Airport and Visa are among those listed as supporters, and the charity states on its website: “We couldn’t achieve what we do without our partners.”

A spokeswoman for Marks & Spencer, which has run a “Shwopping” partnership with Oxfam since 2008, said the chain is monitoring how the charity is dealing with the situation.

She said: “These are very serious allegations. M&S continues to monitor the situation very closely as we seek to understand the steps that Oxfam is taking to address them and develop a robust safeguarding plan for the future.”

The initiative, allowing people to drop unwanted clothes into M&S shops, has seen more than 28 million garments donated in stores and Oxfam shops, worth an estimated £19 million, according to the charity’s website.

Visa, another corporate partner of Oxfam said: “We are engaged with Oxfam to understand what steps have been taken to address staff misconduct and ensure alignment with our own standards and values.”

Oxfam said the partnership with Visa had “transformed the security, speed and efficiency with which Oxfam can distribute life-saving funds to people affected by natural disaster”.

Following Typhoon Haiyan in 2013, which left devastation in its wake in the Philippines, pre-paid cards were given to families, allowing them to buy basics such as food and water.

Heathrow Airport, a partner since 2013, has undertaken various fundraising activities through the years, raising £1 million.

A spokeswoman said in a statement: “We are in touch with the charity and are taking this matter very seriously.”

Waterstones, which helped the charity’s Syria Crisis Appeal, raising £1 million through book sales, pledged its commitment to Oxfam.

A spokeswoman said: “Waterstones remains a committed supporter of Oxfam. The work of the charity, as of its peers, is of great value.

“We listen to, and seek to understand, the assurances given by the Oxfam leadership.”

A spokeswoman for the Co-operative Bank, which has allowed donations to be made through Oxfam credit card payments, said: “We are monitoring the situation closely and are in touch with Oxfam about the issues.”

While the PayPal company logo appears on the charity’s website, a spokesman for the firm said the partnership with Oxfam ended a number of years ago.