LONDON (AP) — The British government on Friday suspended new funding to aid agency Oxfam, which had some staff accused of sexually exploiting people in crisis zones. The group’s chief called the allegations “a stain” that shames the organization.

International Development Secretary Penny Mordaunt said Oxfam had agreed not to bid for further U.K. taxpayer funds until it met the British government’s “high standards.”

“Clearly Oxfam have a long way to go before they can regain the trust of the British public, their staff and the people they aim to help,” she said. “The actions and attitude of the organization over the coming weeks will be critical.”

Oxfam received 31.7 million pounds ($43.8 million) from the British government in 2016-17, out of some 400 million pounds in total income.

U.K.-based Oxfam has been rocked by allegations that senior staff working in Haiti after the country’s 2010 earthquake faced misconduct allegations, including using prostitutes and downloading pornography.

Oxfam says it investigated the case, fired four workers and let three others resign, but the British government and charity regulators have criticized its lack of transparency.

Mordaunt said the government had asked Oxfam and other recipients of aid funding for assurances about their “safeguarding and reporting practices” by Feb. 26.

She said Oxfam had already agreed to report the accused staff members to their respective governments and to hand over all evidence it held on the allegations to the Haitian government.

She said “hundreds of good, brave and compassionate people working for Oxfam around the world” had been “poorly served by Oxfam’s leadership team.”

Oxfam International executive director Winnie Byanyima said she was deeply sorry for the allegations about staff in Haiti, and also in Chad.

“What happened in Haiti and afterwards is a stain on Oxfam that will shame us for years, and rightly so,” Byanyima said.

She said she was appointing an independent commission to “look into our culture and our practices” and set up a vetting system for its staff. Byanyima urged all victims of abuse to come forward.

“I’m here for all the women who have been abused. I want them to come forward and for justice to be done for them,” she told the BBC.

The scandal is a major blow to Oxfam, which relies on public and corporate donations as well as government funding.

South African Nobel laureate Desmond Tutu, British actress Minnie Driver and Senegalese musician Baaba Maal have all resigned as Oxfam celebrity ambassadors in the wake of the sexual misconduct allegations and Britain’s charity regulator has launched an investigation.

The allegations relate to Oxfam GB, one 20 affiliates that make up Oxfam International.

Mark Goldring, chief executive of Oxfam GB, admitted the organization needed to reform, but said “the scale and the intensity of the attacks feels out of proportion to the level of culpability.”

He told The Guardian that the scandal could have “a substantial effect on public confidence, which would affect public donations.”